DIVERSIFICATION OF HUMAN MILK OLIGOSACCHARIDES (HMOs) OR PRECURSORS THEREOF

ABSTRACT

A method of diversification of human milk oligosaccharides (HMOs) or precursors thereof, compounds obtainable by the method, and uses and compositions involving such compounds. The method comprises a) providing at least one compound or a mixture of the compounds selected from the group consisting of: optionally sialylated and/or fucosylated lactose derivatives of general formula 2 and salts thereof; b) adding at least one enzyme comprising a transglycosidase activity to the at least one compound or a mixture of compounds provided according to step a); and c) incubating the mixture obtained according to step b).

FIELD OF THE INVENTION

The present invention relates to a method of diversification of human milk oligosaccharides (HMOs) or precursors thereof and to compounds suitable for use in or obtainable by the method of the present invention. The invention furthermore describes uses of and products involving compounds obtained by the method of the present invention.

BACKGROUND OF THE INVENTION

Human milk oligosaccharides (HMOs) have been the subject of much interest in the past few years. In particular, commercialization efforts for the synthesis of these complex carbohydrates including secreted oligosaccharides have increased significantly due to their roles in numerous biological processes occurring in the human organism. One prominent natural human source of such complex oligosaccharides is mammalian milk. Mammalian milk contains up to 10% carbohydrate, of which the disaccharide, lactose (Gal(β1-4)Glc), is usually a prominent component. Milk and colostrum also contain lesser amounts of other saccharides, referred to as milk oligosaccharides, nearly all of which have a lactose unit at their reducing end to which GlcNAc, Gal, Fuc and/or Neu5Ac or Neu5Gc residues can be attached (Messer and Urashima, 2002, Trends Glycosci. Glycotech, 14, 153-176; and Urashima et al., Advanced Dairy Chemistry, Volume 3: Lactose, Water, Salts and Minor Constituents, 2009, pp. 295-349).

To date, the structures of at least 115 oligosaccharides of human milk have been determined, while mass spectra (MS) data have suggested the presence of almost 130 oligosaccharides in human milk or colostrums (Newburg and Neubauer, 1995, Carohydrates in milks: Analysis, quantities and significance. In: Handbook of Milk Composition (R. G. Jensen, ed.), pp. 273-249, Academic Press, San Diego, USA). Moreover, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) analyses suggest that polysaccharides, consisting of more than 50 monosaccharide residues, as indicated by size exclusion chromatography, are also present in human milk. Therefore, considerably more than 130 different saccharides are probably present in human milk (see also Urashima et al., Advanced Dairy Chemistry, Volume 3: Lactose, Water, Salts and Minor Constituents, 2009, pp. 295-349; and TADASU URASHIMA et al, MILK OLIGOSACCHARIDES, Nova Biomedical Books, New York, 2011, ISBN: 978-1-61122-831-1).

The 115 human milk oligosaccharides, the structures of which have been determined to date, can be grouped into 13 series based on their core structures. Such 13 core structures are exemplarily shown in Table 1 below:

TABLE 1 13 different core structures of human milk oligosaccharides (HMOs) No Core name Core structure 1 lactose (Lac) Galβ1-4Glc 2 lacto-N-tetraose (LNT) Galβ1-3GlcNAcβ1-3Galβ1-4Glc 3 lacto-N-neotetraose Galβ1-4GlcNAcβ1-3Galβ1-4Glc (LNnT) 4 lacto-N-hexaose (LNH) Galβ1-3GlcNAcβ1-3(Galβ1-4GlcNAcβ1-6)Galβ1-4Glc 5 lacto-N-neohexaose Galβ1-4GlcNAcβ1-3(Galβ1-4GlcNAcβ1-6)Galβ1-4Glc (LNnH) 6 para-lacto-N-hexaose Galβ1-3GlcNAcβ1-3Galβ1-4GlcNAcβ1-3Galβ1-4Glc (para-LNH) 7 para-lacto-N- Galβ1-4GlcNAcβ1-3Galβ1-4GlcNAcβ1-3Galβ1-4Glc neohexaose (para- LNnH) 8 lacto-N-octaose (LNO) Galβ1-3GlcNAcβ1-3(Galβ1-4GlcNAcβ1-3Galβ1-4GlcNAcβ1- 6)Galβ1-4Glc 9 lacto-N-neooctaose Galβ1-4GlcNAcβ1-3(Galβ1-3GlcNAcβ1-3Galβ1-4GlcNAcβ1- (LNnO) 6)Galβ1-4Glc 10 Iso-lacto-N-octaose Galβ1-3GlcNAcβ1-3(Galβ1-3GlcNAcβ1-3Galβ1-4GlcNAcβ1- (iso-LNO) 6)Galβ1-4Glc 11 para-lacto-N-octaose Galβ1-3GlcNAcβ1-3Galβ1-4GlcNAcβ1-3Galβ1-4GlcNAcβ1- (para-LNO) 3Galβ1-4Glc 12 lacto-N-neodecaose Galβ1-3GlcNAcβ1-3[Galβ1-4GlcNAcβ1-3(Galβ1- (LNnD) 4GlcNAcβ1-6)Galβ1-4GlcNAcβ1-6]Galβ1-4Glc 13 lacto-N-decaose (LND) Galβ1-3GlcNAcβ1-3[Galβ1-3GlcNAcβ1-3(Galβ1- 4GlcNAcβ1-6)Galβ1-4GlcNAcβ1-6]Galβ1-4Glc

As found by Urashima et al. (see also Urashima et al., Advanced Dairy Chemistry, Volume 3: Lactose, Water, Salts and Minor Constituents, 2009, pp. 295-349; and TADASU URASHIMA et al, MILK OLIGOSACCHARIDES, Nova Biomedical Books, New York, 2011, ISBN: 978-1-61122-831-1) the many variations of the oligosaccharides are constructed by the addition of a Neu5Acβ2-3/2-6 residue to Gal or GlcNAc, and of Fucα1-2/1-3/1-4 to Gal, GlcNAc or a reducing Glc of the core units. The main structural features of human milk oligosaccharides are the presence of oligosaccharides containing the type I unit (Gal(β1-3)GlcNAc), as well as those containing the type II unit (Gal(β1-4)GlcNAc), and oligosaccharides containing the type I predominate over those containing the type II unit. The milk oligosaccharides of other species investigated to date mostly exhibit the type II but not the type I unit.

The large variety of oligosaccharides in human milk and colostrum and the difference to other species, however, makes it difficult to prepare suitable replacements in foods, particularly in infant food formulae, which display at least part of the entire spectrum of human milk oligosaccharides. Furthermore, their recognized importance in the maturation of the immune system and their prognostic use as immunomodulators underlines their importance as a possible immunomodulator.

Accordingly, there is an urgent need in the art for the preparation of complex oligosaccharides and mixtures thereof, which resemble as much as possible or even reproduce the variety of complex oligosaccharides in human milk.

Many attempts have been carried out in this respect to produce individual HMOs via organo-chemical synthesis and, due to its stereoselectivity, via enzymatic means. Enzymatic means have been increasingly explored in the last two decades.

Notably, in biological systems, Leloir-type glycosyltransferases (GTs, EC 2.4.1.-) and glycosidases (also called glycoside hydrolases: GHs, EC 3.2.1.-) constitute the two major classes of carbohydrate-processing enzymes, which may be utilized in the production of HMOs. Both classes of enzymes act to transfer a glycosyl group from a donor to an acceptor resulting in oligosaccharide production. The use of glycosyltransferases for synthesis in industrial processes, however, is limited both by the availability of the desired enzymes due to problems with expression and solubility and the high costs of the activated donor sugars. These nucleotide donors may be typically generated in situ, but the process requires additional enzymes (see Hanson, S., et al., Trends Biochem Sci, 2004. 29(12): p. 656-63). In contrast to glycosyltransferases, glycosidases have a wide range of donor substrates employing usually monosaccharides, oligosaccharides or/and engineered substrates (i.e. substrates carrying various functional groups). They often display activity towards a large variety of carbohydrate and non-carbohydrate acceptors. Another advantage of the use of glycosidases compared to glycosyltransferases is their robustness and accessibility.

In vivo, glycosidases usually catalyze the hydrolysis of glycosidic linkages with either retention or inversion of stereochemical configuration in the product. In vitro, they can catalyse the formation of a new glycosidic bond either by transglycosylation or by reverse hydrolysis (ie. condensation). Under kinetically controlled reactions these enzymes (typically, retaining glycosidases) can be used to form glycosidic linkages using a glycosyl donor activated by a good anomeric leaving group (e.g. nitrophenyl glycoside). In contrast, the thermodynamically controlled reverse hydrolysis uses high concentrations of free sugars. However, even though the appropriate application of glycosidases in the synthetic direction is of considerable interest, it remains challenging as optimal conditions and suitable substrates have to be found to drive the reaction in the desired direction and to avoid hydrolysis of the products.

Another approach to overcome this bottleneck and to make glycosidases more suitable for oligosaccharide synthesis has been recently developed by providing modified enzymes (variants). Thus, during these two past decades, protein engineering based on rational or combinatorial techniques has proven to be extremely powerful to generate biocatalysts with improved transglycosylation activity and efficiency.

However, even though many organo-chemical syntheses or enzyme based syntheses for basic human milk oligosaccharide structures or their precursors have been published meanwhile (e.g. for the synthesis of some individual sialylated HMOs or HMO benzyl/substituted benzyl glycosides using a trans-sialidase and 3′-SL see WO 93/18787 and WO 2012/007588), such synthesis methods still do not allow the preparation of complex mixtures of naturally occurring oligosaccharides or derivatives thereof. Preparing such mixtures on the basis of individually designed syntheses of single HMOs is furthermore costly and may not resemble the large variety of naturally occurring HMOs.

Accordingly, it is an object underlying the present invention to provide a method, which allows provision of a larger variety of human milk oligosaccharides than prior art methods, preferably in a cost efficient manner, and preferably on an industrial scale.

Further, the provision of oligosaccharides and mixtures of oligosaccharides having between 4 and 12 saccharide units, such as between 6 and 10 saccharide units, in a setereoselective fashion and in a cost effective manner suitable to large scale production of oligosaccharides is desirable.

BRIEF DESCRIPTION OF THE FIGURES

The following figures are intended to illustrate the invention further. They are not intended to limit the subject matter of the invention thereto.

FIG. 1: depicts the presently known 13 core structures of human milk oligosaccharides (HMOs).

FIG. 2: depicts an exemplary synthesis of HMOs using lactose, N-acetyllactosaminyl donor and lacto-N-biosyl donor with the enzymes β-1,3-trans-lacto-N-biosidase, β-1,3-trans-N-acetyllactosaminidase, and β-1,6-trans-N-acetyllactosaminidase.

DESCRIPTION OF THE INVENTION

According to a first aspect, the present invention provides a method for diversification of human milk oligosaccharides (HMOs) or precursors thereof, namely a method for preparation of one or more human milk oligosaccharides (HMOs) or derivatives or precursors thereof, the method comprising the steps of

-   a) providing at least one compound or a mixture of compounds     selected from the group consisting of:     -   optionally sialylated and/or fucosylated lactose derivatives of         general formula 2 and salts thereof:

-   -   wherein     -   R is a group removable by hydrogenolysis,     -   R₁ independently of each other is fucosyl or H     -   R₄ independently of each other is sialyl or H,     -   provided that the compound of general formula 2 is not         R-glycoside of lactose, if provided alone;     -   optionally sialylated and/or fucosylated lactose derivatives of         general formula 4 and salts thereof:

-   -   wherein     -   R₁ independently of each other is fucosyl or H     -   R₄ independently of each other is sialyl or H,     -   provided that the compound of general formula 4 is not lactose,         if provided alone;     -   lacto-N-tetraose (LNT):

-   -   lacto-N-tetraose (LNT) derivatives of the following formula:

-   -   wherein R is a group removable by hydrogenolysis;     -   lacto-N-neotetraose (LNnT):

-   -   lacto-N-neotetraose (LNnT) derivatives of the following formula:

-   -   wherein R is a group removable by hydrogenolysis;

-   b) adding at least one enzyme comprising a transglycosidase activity     to the at least one compound or mixture of compounds provided     according to step a);

-   c) incubating the mixture obtained according to step b);

-   d) optionally repeating at least steps a) and c) or steps b) and c)     with the mixture obtained according to step c);

-   e) optionally subjecting the incubated mixture obtained after     step c) or d) to a hydrogenolysis reaction.

Preferably, in the compound of formula 2 at least one of R₁ or R₄ is not H.

Likewise preferably, in the compound of formula 4 at least one of R₁ or R₄ is not H.

According to a preferred embodiment of the first aspect, the present invention provides a method for diversification of human milk oligosaccharides (HMOs) or precursors thereof, namely a method for preparation of one or more human milk oligosaccharides (HMOs) or derivatives or precursors thereof, the method comprising the steps of:

-   -   a) providing at least one compound or a mixture of the compounds         selected from the group consisting of:         -   optionally sialylated and/or fucosylated lactose derivatives             of general formula 2 and salts thereof:

-   -   wherein     -   R is a group removable by hydrogenolysis,     -   R₁ independently of each other is fucosyl or H     -   R₄ independently of each other is sialyl or H,     -   provided that the compound of general formula 2 is not         R-glycoside of lactose, if provided alone;         -   optionally sialylated and/or fucosylated lactose derivatives             of general formula 4 and salts thereof:

-   -   wherein     -   R₁ independently of each other is fucosyl or H     -   R₄ independently of each other is sialyl or H,     -   provided that the compound of general formula 4 is not lactose,         if provided alone;         -   lacto-N-tetraose (LNT):

-   -   -   lacto-N-tetraose (LNT) derivatives of the following formula:

-   -   wherein R is a group removable by hydrogenolysis;         -   lacto-N-neotetraose (LNnT):

-   -   -   lacto-N-neotetraose (LNnT) derivatives of the following             formula:

-   -   wherein R is a group removable by hydrogenolysis;     -   b) adding at least one enzyme comprising a transglycosidase         activity to the at least one compound or mixture of compounds         provided according to step a);     -   c) incubating the mixture obtained according to step b);     -   d) wherein, where both: only two compounds are provided in         step a) of which one is 3′-sialyllactose, and the enzyme         comprising a transglycosidase activity added in step b) is an         enzyme comprising a trans-sialidase activity; at least steps a)         and c) or steps b) and c) are repeated;     -   e) optionally repeating at least steps a) and c) or steps b)         and c) with the mixture obtained according to step c) or d);     -   f) optionally subjecting the mixture obtained after step c), d)         or e) to a hydrogenolysis reaction.

Preferably, in the compound of formula 2 at least one of R₁ or R₄ is not H.

Likewise preferably, in the compound of formula 4 at least one of R₁ or R₄ is not H.

According to the preferred embodiment above, at least one more additional incubation cycle is needed when both: only two compounds are provided in step a), of which one is 3′-sialyllactose, and the enzyme provided in step b) is an enzyme comprising a trans-sialidase activity. When repeating step a), the at least one compound added according to step a) is preferably different from that/those provided in the first cycle; when repeating step b), the at least one enzyme added according to step b) is preferably different from that provided in the first cycle. Thus, the production of mixtures of oligosaccharides is achieved in a simple process capable of being conducted on a large scale. In addition, the production of longer chain oligosaccharides comprising sialyl moiety/moieties and mixtures thereof, such as oligosaccharides containing 4-12 saccharide units, or 6-10 saccharide units, can be achieved simply and on a large scale.

In certain cases, the preferred embodiment above relates to a method for diversification of human milk oligosaccharides (HMOs) or precursors thereof, namely a method for preparation of one or more human milk oligosaccharides (HMOs) or derivatives or precursors thereof, the method comprising the steps of:

-   -   a) providing at least one compound or a mixture of the compounds         selected from the group consisting of:         -   optionally sialylated and/or fucosylated lactose derivatives             of general formula 2 and salts thereof:

-   -   -   wherein         -   R is a group removable by hydrogenolysis,         -   R₁ independently of each other is fucosyl or H         -   R₄ independently of each other is sialyl or H,         -   provided that the compound of general formula 2 is not             R-glycoside of lactose, if provided alone;         -   optionally sialylated and/or fucosylated lactose derivatives             of general formula 4 and salts thereof:

-   -   -   wherein         -   R₁ independently of each other is fucosyl or H         -   R₄ independently of each other is sialyl or H,         -   provided that the compound of general formula 4 is not             lactose, if provided alone;         -   lacto-N-tetraose (LNT):

-   -   -   lacto-N-tetraose (LNT) derivatives of the following formula:

-   -   -   wherein R is a group removable by hydrogenolysis;         -   lacto-N-neotetraose (LNnT):

-   -   -   lacto-N-neotetraose (LNnT) derivatives of the following             formula:

-   -   -   wherein R is a group removable by hydrogenolysis;

    -   b) adding at least one enzyme comprising a transglycosidase         activity to the at least one compound or mixture of compounds         provided according to step a);

    -   c) incubating the mixture obtained according to step b);

    -   d) wherein, where both: only two compounds are provided in         step a) of which one is a sialylated lactose derivative of         general formula 2 or 4, and the enzyme comprising a         transglycosidase activity added in step b) is an enzyme         comprising a trans-sialidase activity; at least steps a) and c)         or steps b) and c) are repeated;

    -   e) optionally repeating at least steps a) and c) or steps b)         and c) with the mixture obtained according to step c) or d);

    -   f) optionally subjecting the mixture obtained after step c), d)         or e) to a hydrogenolysis reaction.

Preferably, in the compound of formula 2 at least one of R₁ or R₄ is not H.

Likewise preferably, in the compound of formula 4 at least one of R₁ or R₄ is not H.

According to the preferred embodiment above, at least one more additional incubation cycle is needed when both: only two compounds are provided in step a), of which one is sialylated lactose derivative of general formula 2 or 4, and the enzyme provided in step b) is an enzyme comprising a trans-sialidase activity. When repeating step a), the at least one compound added according to step a) is preferably different from that/those provided in the first cycle; when repeating step b), the at least one enzyme added according to step b) is preferably different from that provided in the first cycle. Thus, the production of mixtures of oligosaccharides is achieved in a simple process capable of being conducted on a large scale. In addition, the production of longer chain oligosaccharides comprising sialyl moiety/moieties and mixtures thereof, such as oligosaccharides containing 4-12 saccharide units, or 6-10 saccharide units, can be achieved simply and on a large scale.

In certain cases, the preferred embodiment above relates to a method for diversification of fucosylated human milk oligosaccharides (HMOs) or precursors thereof, namely a method for preparation of one or more fucosylated human milk oligosaccharides (HMOs) or derivatives or precursors thereof, the method comprising the steps of:

-   -   a) providing at least one compound or a mixture of the compounds         characterized by general formula 5

-   -   -   R′ independently is fucosyl or H, with the proviso that at             least one R′ is fucosyl, and R* is a group removable by             hydrogenolysis or H, and

    -   optionally providing at least one compound or a mixture of the         compounds, selected from the group consisting of:

    -   optionally sialylated lactose derivatives of general formula 6         and salts thereof:

-   -   wherein     -   R* is a group removable by hydrogenolysis or H,     -   R″ independently of each other is sialyl or H,         -   lacto-N-tetraose (LNT):

-   -   -   lacto-N-tetraose (LNT) derivatives of the following formula:

-   -   wherein R is a group removable by hydrogenolysis;         -   lacto-N-neotetraose (LNnT):

-   -   -   lacto-N-neotetraose (LNnT) derivatives of the following             formula:

-   -   wherein R is a group removable by hydrogenolysis;     -   b) adding at least one enzyme comprising a transfucosidase         activity to the at least one compound or mixture of compounds         provided according to step a);     -   c) incubating the mixture obtained according to step b);     -   d) optionally subjecting the mixture obtained after step d) to a         hydrogenolysis reaction.

According to the preferred embodiment above, the production of single fucosylated human milk oligosaccharides (HMO) or derivatives or precursors thereof or mixtures of fucosylated human milk oligosaccharides (HMOs) or derivatives or precursors thereof is achieved in a simple process capable of being conducted on a large scale. Particularly preferably, 2′-fucosyllactose or 3-fucosyllactose is provided in step a) and one further compound is also provided which compound is selected from the group consisting of 2′-fucosyllactose, 3-fucosyllactose, 3′-sialyllactose, 6′-siallyllactose, LNT and LNnT.

The preferred method above leads to the formation of one or more fucosylated human milk oligosaccharides (HMOs) or derivatives or precursors thereof, preferably to the formation of a fucosylated human milk oligosaccharide (HMO) or derivative or precursor thereof, more prefereably to the formation of a fucosylated human milk oligosaccharide, particularly to the formation of 2′,3-difucosyllactose, 3-fucosyl-3-sialyllactose, fucosylated LNT or fucosylated LNnT.

In certain cases, the preferred embodiment above relates to a method for diversification of human milk oligosaccharides (HMOs) or precursors thereof, namely a method for preparation of one or more human milk oligosaccharides (HMOs) or derivatives or precursors thereof, the method comprising the steps of:

-   -   a) providing at least one compound or a mixture of the compounds         selected from the group comprising:         -   optionally sialylated and/or fucosylated lactose derivatives             of general formula 2 and salts thereof:

-   -   wherein     -   R is a group removable by hydrogenolysis,     -   R₁ independently of each other is fucosyl or H     -   R₄ independently of each other is sialyl or H,     -   provided that the compound of general formula 2 is not         R-glycoside of lactose, if provided alone;         -   optionally sialylated and/or fucosylated lactose derivatives             of general formula 4 and salts thereof:

-   -   wherein     -   R₁ independently of each other is fucosyl or H     -   R₄ independently of each other is sialyl or H,     -   provided that the compound of general formula 4 is not lactose,         if provided alone;         -   lacto-N-tetraose (LNT):

-   -   -   lacto-N-tetraose (LNT) derivatives of the following formula:

-   -   wherein R is a group removable by hydrogenolysis;         -   lacto-N-neotetraose (LNnT):

-   -   -   lacto-N-neotetraose (LNnT) derivatives of the following             formula:

-   -   wherein R is a group removable by hydrogenolysis;     -   b) adding at least one enzyme comprising a transglycosidase         activity to the at least one compound or mixture of compounds         provided according to step a);     -   c) incubating the mixture obtained according to step b);     -   d) wherein, where both: only two compounds are provided in         step a) of which one is a fucosylated lactose derivative of         general formula 2 or 4, and the enzyme comprising a         transglycosidase activity added in step b) is an enzyme         comprising a trans-fucosidase activity; at least steps a) and c)         or steps b) and c) are repeated;     -   e) optionally repeating at least steps a) and c) or steps b)         and c) with the mixture obtained according to step c) or d);     -   f) optionally subjecting the mixture obtained after step c), d)         or e) to a hydrogenolysis reaction.

Preferably, in the compound of formula 2 at least one of R₁ or R₄ is not H.

Likewise preferably, in the compound of formula 4 at least one of R₁ or R₄ is not H.

According to the preferred embodiment above, at least one more additional incubation cycle is needed when both: only two compounds are provided in step a), of which one is a fucosylated lactose derivative of general formula 2 or 4, and the enzyme provided in step b) is an enzyme comprising a trans-fucosidase activity. When repeating step a), the at least one compound added according to step a) is preferably different from that/those provided in the first cycle; when repeating step b), the at least one enzyme added according to step b) is preferably different from that provided in the first cycle. Thus, the production of mixtures of oligosaccharides is achieved in a simple process capable of being conducted on a large scale. In addition, the production of longer chain oligosaccharides comprising fucosyl moiety/moieties and mixtures thereof, such as oligosaccharides containing 4-12 saccharide units, or 6-10 saccharide units, can be achieved simply and on a large scale.

According to a more preferred embodiment of the first aspect, the present invention provides a method for diversification of human milk oligosaccharides (HMOs) or precursors thereof, namely a method for preparation of a mixture of a plurality of human milk oligosaccharides (HMOs) or derivatives or precursors thereof, the method comprising the steps of:

-   -   a) providing at least one compound or a mixture of compounds         selected from the group comprising:         -   optionally sialylated and/or fucosylated lactose derivatives             of general formula 2 and salts thereof:

-   -   -   wherein         -   R is a group removable by hydrogenolysis,         -   R₁ independently of each other is fucosyl or H         -   R₄ independently of each other is sialyl or H,         -   provided that the compound of general formula 2 is not an             R-glycoside of lactose, if provided alone;         -   optionally sialylated and/or fucosylated lactose derivatives             of general formula 4 and salts thereof:

-   -   -   wherein         -   R₁ independently of each other is fucosyl or H         -   R₄ independently of each other is sialyl or H,         -   provided that the compound of general formula 4 is not             lactose, if provided alone;         -   lacto-N-tetraose (LNT):

-   -   -   lacto-N-tetraose (LNT) derivatives of the following formula:

-   -   -   wherein R is a group removable by hydrogenolysis; and         -   lacto-N-neotetraose (LNnT):

-   -   -   lacto-N-neotetraose (LNnT) derivatives of the following             formula:

-   -   -   wherein R is a group removable by hydrogenolysis;

    -   b) adding at least one enzyme comprising a transglycosidase         activity to the at least one compound or a mixture of compounds         provided according to step a);

    -   c) incubating the mixture obtained according to step b);

    -   d) wherein,         -   if only one HMO or derivative or precursor thereof is made             as a result of step c), and further         -   where both: only two compounds are provided in step a) of             which one is 3′-sialyllactose or a sialylated lactose             derivative of general formula 2 or 4, and the enzyme             comprising a transglycosidase activity added in step b) is             an enzyme comprising a trans-sialidase activity,

    -   at least steps a) and c) or steps b) and c) are repeated;

    -   e) optionally repeating at least steps a) and c) or steps b)         and c) with the mixture obtained according to step c) or d);

    -   f) optionally subjecting the mixture obtained after step c), d)         or e) to a hydrogenolysis reaction.

Preferably, in the compound of formula 2 at least one of R₁ or R₄ is not H.

Likewise preferably, in the compound of formula 4 at least one of R₁ or R₄ is not H.

According to the more preferred embodiment above, at least one more additional incubation cycle is needed when only one product (HMO, HMO derivative or HMO precursor) is formed after the first incubation cycle. This case may occur in some donor-acceptor pairs provided in step a). The formation of a single product allows the presence of starting material(s) provided in step a) remaining in the mixture obtained in step c). When repeating steps a) and c), the at least one compound added according to step a) is preferably different from that/those provided in the first cycle; when repeating steps b) and c), the at least one enzyme added according to step b) is preferably different from that provided in the first cycle. When repeating all of steps a) to c), suitably either the at least one compound provided in step a) or the at least one enzyme provided in step b) are different from those provided in the first cycle, and preferably both are different from those provided in the first cycle.

The more preferred embodiment provides a process in which mixtures of HMOs or precursors thereof can be produced simply in a single reaction process which is capable of being carried out on a large scale.

In the context of the present invention the expression “group removable by hydrogenolysis” refers to groups whereby a carbon-oxygen single bond is cleaved or undergoes “lysis” by hydrogen. Hydrogenolysis represents an exception among protecting group chemistries, in which water can be used as a solvent. Hydrogenolysis itself is a powerful deprotection process suitable to remove O-benzyl/substituted O-benzyl moieties from an oligosaccharide scaffold in almost a quantitative manner under extremely gentle conditions preventing by-product formation. It is also an advantage of hydrogenolysis as a final deblocking procedure within a complex synthetic pathway that only catalytic amount of reagents are required for the completion of the reaction providing exclusively toluene or substituted toluene derivatives as by-products. Both toluene and substituted toluene derivatives can easily be removed even in multi ton scales from water soluble oligosaccharide products via evaporation and/or extraction processes. Suitable groups for hydrogenolysis may include benzyl, diphenylmethyl (benzhydryl), 1-naphthylmethyl, 2-naphthylmethyl or triphenylmethyl (trityl) groups, each of which may be optionally substituted by one or more groups selected from: alkyl, alkoxy, phenyl, amino, acylamino, alkylamino, dialkylamino, nitro, carboxyl, alkoxycarbonyl, carbamoyl, N-alkylcarbamoyl, N,N-dialkylcarbamoyl, azido, halogenalkyl or halogen. Preferably, such substitution, if present, is on the aromatic ring(s). A particularly preferred protecting group is benzyl optionally substituted with one or more groups selected from alkyl or halogen. More preferably, the protecting group is selected from unsubstituted benzyl, 4-chlorobenzyl and 4-methylbenzyl. These particularly preferred and more preferable protecting groups have the advantage that the by-products of the hydrogenolysis are exclusively toluene or substituted toluene. Such by-products can easily be removed even in multi ton scales from water soluble oligosaccharide products via evaporation and/or extraction processes. Hydrogenolysis may be carried out by adding catalytic amounts of palladium, Raney nickel or another appropriate metal catalyst known for use in hydrogenolysis, resulting in the regeneration of the OH group. Groups of this type are well known to the skilled man and thoroughly discussed (see e.g. P. G. M. Wuts and T. W. Greene: Protective Groups in Organic Synthesis, John Wiley & Sons (2007)).

Furthermore, the term “R-glycoside of lactose” is to be understood as lactose which has been modified with a residue R to form a glycoside via a glycosidic bond.

Furthermore, the term “HMO precursor” means an R-glycoside of an HMO, which has been modified with a residue R to form a glycoside via a glycosidic bond.

Furthermore, the term “HMO derivative” means an oligosaccharide structurally similar to a HMO and R-glycosides thereof, preferably derivatives according to general formula 1, 2, 3 and 4.

Additionally, the term “fucosyl” within the context of the present invention means a L-fucopyranosyl group attached to the core oligosaccharide with α-interglycosidic linkage:

“N-acetyl-lactosaminyl” group within the context of the present invention means the glycosyl residue of N-acetyl-lactosamine (LacNAc, Galpβ1-4GlcNAcp) linked with β-linkage:

Furthermore, the term “lacto-N-biosyl” group within the context of the present invention means the glycosyl residue of lacto-N-biose (LNB, Galpβ1-3GlcNAcp) linked with β-linkage:

The term “sialyl” within the context of the present invention means the glycosyl residue of sialic acid (N-acetyl-neuraminic acid, Neu5Ac) linked with α-linkage:

Additionally, the term “glycosyl residue comprising one or more N-acetyl-lactosaminyl and/or one or more lacto-N-biosyl units” within the context of the present invention means a linear or branched structure comprising the said units that are linked to each other by interglycosidic linkages.

According to step a) of the first aspect, including the preferred and more preferred embodiments, at least one compound or a mixture of compounds is provided. Such a mixture of compounds is preferably to be understood as a mixture of at least two, three, four, five, one to five, five to ten, one to ten, two to ten, two to twenty, three to twenty, four or even five to twenty, or even more different compounds as generally defined according to any of the compounds of step a). Accordingly, such at least one compound or a mixture of at least two, three, four, five, one to five, five to ten, one to ten, two to ten, two to twenty, three to twenty, four or even five to twenty, or even more different compounds as generally defined according to any of the compounds of step a) may be selected without restriction from any of the compounds as defined according to any of formulae 2 and/or 4 or from LNT, LNnT, or LNT derivatives or LNnT derivatives as defined above.

Components as defined according to step a) of the first aspect, including the preferred and more preferred embodiments, particularly components as defined according to any of formulae 2 or 4 or any of compounds LNT, LNnT, or LNT derivatives or LNnT derivatives as defined above, may serve as a donor or as an acceptor in the method of the present invention for diversification of human milk oligosaccharides (HMOs) or derivatives or precursors thereof. In the context of the present invention, the term “donor” is preferably understood as a compound, which provides a specific moiety in a chemical reaction, e.g. a nucleophilic or electrophilic substitution reaction, to a further compound, preferably an acceptor. Likewise, the term “acceptor” is preferably understood as a compound, which receives a specific moiety in a chemical reaction, e.g. nucleophilic or electrophilic substitution reaction, to a further compound, preferably a donor.

Particularly preferably, compounds according to formula 2 as defined above

for use in step a) of the first aspect, including the preferred and more preferred embodiments, for diversification of human milk oligosaccharides (HMOs) may be selected from the group of: R-glycosides of 2′-fucosyllactose (2′-FL), 3-fucosyllactose (3-FL), 2′,3-difucosyllactose (DF-L), 3′-sialyllactose (3′-SL), 6′-sialyllactose (3′-SL) and 3′-sialyl-3-fucosyllactose (FSL) or salts thereof. The R-glycosides may be alpha or beta-anomers. Preferably, said R-glycosides are the beta-anomers. These R-glycosides represent naturally occurring HMOs having a lactose core. Compounds for use in step a) of the method for diversification of human milk oligosaccharides (HMOs) of the present invention may preferably be selected from compounds as defined above, more preferably from compounds according to general formula 2, wherein R is benzyl.

Also particularly preferably, compounds employed in step a) of the first aspect, including the preferred and more preferred embodiments, for diversification of human milk oligosaccharides (HMOs), may be selected from a compound according to general formula 4 and salts thereof.

Particularly preferred compounds according to formula 4 as defined above for use in step a) of the method of the present invention for diversification of human milk oligosaccharides (HMOs) may be selected from the group of: 2′-fucosyllactose (2′-FL), 3-fucosyllactose (3-FL), 2′,3-difucosyllactose (DFL), 3′-sialyllactose (3′-SL), 6′-sialyllactose (6′-SL), 3′-sialyl-3-fucosyllactose (FSL) and salts thereof.

In step b) of the first aspect, including the preferred and more preferred embodiments, for diversification of human milk oligosaccharides (HMOs) at least one enzyme comprising a transglycosidase activity is added to the at least one compound or the mixture obtained or provided according to step a). Such an incubation advantageously allows diversification of the at least one compound or the mixture obtained or provided according to step a). Diversification of such at least one compound or the mixture obtained or provided according to step a) is based on the different activities of the enzymes added during step b) but also on the at least one compound or the mixture obtained or provided according to step a), each of which compounds may serve as a donor or as an acceptor in the diversification reaction. Utilizing this approach, the method of the present invention advantageously allows variation and thus diversification of the number and type of oligosaccharides contained in the mixture in a simple and cost efficient manner. The use of enzymes furthermore allows carrying out the diversification in a stereoselective manner. Diversification may occur preferably by transferring glycosyl moieties (eg, a sialyl moiety, a fucosyl moiety, an N-acetyllactosaminyl moiety, or a lacto-N-biosyl moiety) by forming new bonds at desired positions of the molecule, etc., in a well defined manner to obtain a mixture of diversified human milk oligosaccharides or derivatives thereof.

In step b) of the first aspect, including the preferred and more preferred embodiments, at least one enzyme comprising transglycosidase activity is added, preferably at least two, three, four, five, two to five, two to ten, two to twenty, five to ten or even more different enzymes comprising transglycosidase activity.

Enzymes suitable in step b) of the first aspect, including the preferred and more preferred embodiments, for diversification of human milk oligosaccharides (HMOs) typically comprise at least one enzyme comprising a transglycosidase activity, preferably selected from enzymes having, e.g. a fucosidase or trans-fucosidase, a sialidase (neuraminidase) or trans-sialidase (transneuraminidase), a lacto-N-biosidase or trans-lacto-N-biosidase and/or a N-acetyllactoaminidase or trans-N-acetyllactoaminidase activity, or any further enzyme having such an activity. Even more preferably, enzymes suitable in step b) of the first aspect, including the preferred and more preferred embodiments, for diversification of human milk oligosaccharides (HMOs) may be selected from the group comprising wild type or mutated glycosidases or transglycosidases, preferably wild type or mutated glycosidases or transglycosidases having a fucosidase or trans-fucosidase, a sialidase (neuraminidase) or trans-sialidase (transneuraminidase), a lacto-N-biosidase or trans-lacto-N-biosidase and/or a N-acetyllactoaminidase or trans-N-acetyllactoaminidase activity, or preferably having α-trans-fucosidase, α-trans-sialidase, β-trans-lacto-N-biosidase and/or β-trans-N-acetyllactosaminidase activity.

Enzymes suitable in step b) of the first aspect, including the preferred and more preferred embodiments, for diversification of human milk oligosaccharides (HMOs) further may be selected from any genus known to a skilled person, to express or secrete at least one enzyme as defined above, e.g. an enzyme having a transglycosidase activity, preferably an enzyme having a fucosidase or trans-fucosidase, a sialidase (neuraminidase) or trans-sialidase (transneuraminidase), a lacto-N-biosidase or trans-lacto-N-biosidase and/or a N-acetyllactoaminidase or trans-N-acetyllactoaminidase activity, or preferably having α-trans-fucosidase, α-trans-sialidase, β-trans-lacto-N-biosidase and/or β-trans-N-acetyllactosaminidase activity, or any further enzyme having such an activity. Even more preferably, such enzymes suitable in step b) of the method of the present invention for diversification of human milk oligosaccharides (HMOs) may be selected from bacteria selected from Bacillus, Bdobacterium, Lactobacillus, Leuconostoc, Lactococcus, Streptococcus, Streptomyces, Sulfolobus, Thermotoga, or Trypanosoma.

Even more preferably, such enzymes suitable in step b) of the first aspect, including the preferred and more preferred embodiments, for diversification of human milk oligosaccharides (HMOs) are selected from the group comprising the bacteria Bacillus circulans, Streptomyces sp., Sulfolobus solfataricus P2, Thermotoga maritima MSB8, Trypanosoma cruzi, lactic acid bacteria, such as Bifidobacterium bifidum JCM 1254, Bifidobacterium bifidum NCIMB 41171, Bifidobacterium bifidum NCIMB 41171, Bifidobacterium bifidum JCM1254, Bifidobacterium bifidum JCM1254, Bifidobacterium bifidum PRL2010, Bifidobacterium bifidum PRL2010, Bifidobacterium bifidum S17, Bifidobacterium bifidum S17, Bifidobacterium dentium Bd1, Bifidobacterium longum subsp. infantis ATCC 15697, Bifidobacterium longum subsp longum JDM 301, Bifidobacterium longum subsp. infantis JCM 1222, and Lactobacillus casei BL23.

Particularly preferred microorganisms in the above context respect, particularly for targeted glycosidases/transglycosidases, comprise lactic acid bacteria. Lactic acid bacteria, and more particularly bacteria from the genus Bifidobacterium contain a series of glycosidases including α-2,3/6 sialidases (GH33), α-1,2/3/4 fucosidases (GH29 and GH95), lacto-N-biosidases (GH20), β-galactosidases (GH2) and β-N-acetylhexosaminidases (GH20) that are able to recognize human milk oligosaccharides. Depending on the bifidobacteria strains, these glycosidases are intra- or extracellular enzymes.

A further aspect regarding the use of glycosidases from lactic acid bacteria concerns the industrial importance of such bacteria since they have the GRAS (generally recognized as safe) status. According to another more preferred aspect the glycosidase displaying a trans-fucosidase, trans-sialidase, trans-lacto-N-biosidase and/or trans-N-acetyllactosaminidase activity, preferably a α-trans-fucosidase, α-trans-sialidase, β-trans-lacto-N-biosidase and/or β-trans-N-acetyllactosaminidase activity, is a wild type or an engineered glycosidase, most preferably the wild type glycosidase is taken from the group consisting of lactic acid bacteria, wherein the glycosidase is converted to a transglycosidase by rational engineering or/and directed evolution. A glycosidase selected from the group consisting of lactic acid bacteria is most preferably a glycosidase from Bifidobacterium, Lactobacillus, Lactococcus, Streptococcus or Leuconostoc. A glycosidase selected from the genus Bifidobacterium is most preferably a glycosidase from Bifidobacterium longum subsp. Infantis, Bifidobacterium longum subsp. Longum, Bifidobacterium breve, Bifidobacterium bifidum and Bifidobacterium catenulatum.

Furthermore, engineered fucosidases from thermophilic organisms such as Sulfolobus solfataricus and Thermotoga maritima have recently been developed, which may be used in the method of the present invention. These thermostable glycosidases have considerable potential for industrial applications since they can be used in biotechnological processes at elevated temperatures, and so facilitating the process, preventing risk of contamination, increasing the solubility of the compounds used in the reaction.

According to another more preferred aspect the glycosidase displaying a trans-fucosidase, trans-sialidase, trans-lacto-N-biosidase and/or trans-N-acetyllactosaminidase activity, preferably a α-trans-fucosidase, α-trans-sialidase, β-trans-lacto-N-biosidase and/or β-trans-N-acetyllactosaminidase activity, is a wild type or an engineered glycosidase, most preferably the wild type glycosidase is taken from the group consisting of thermophilic organisms, which glycosidase is converted to a transglycosidase by rational engineering or/and directed evolution. An α-L-fucosidase selected from thermophilic organisms is most preferably an α-L-fucosidase from Thermotoga maritima and Sulfolobus solfataricus.

Preferably, the at least one enzyme comprising a transglycosidase activity may be selected from an enzyme exhibiting a fucosidase or trans-fucosidase activity, preferably as described in the following. In this context, enzymes having a fucosidase or trans-fucosidase activity, more preferably an α-trans-fucosidase activity, are preferably selected from fucosidases in general, even more preferably from α-L-fucosidases, e.g. α-L-fucosidases as classified according to EC 3.2.1.38 and 3.2.1.51. α-L-Fucosidases are widely spread in living organisms such as mammals, plants, fungi and bacteria. These enzymes belong to the families 29 and 95 of the glycoside hydrolases (GH29 and GH95) as defined by the CAZY nomenclature (http://www.cazy.org). Fucosidases from GH 29 are retaining enzymes (3D structure: (β/α)₈) whereas fucosidases from GH 95 are inverting enzymes (3D structure: (α/α)₆). The substrate specificity of the GH29 family is broad whereas that of the GH95 family is strict to α1,2-linked fucosyl residues. The GH29 family seems to be divided into two subfamilies. One subfamily typically has strict specificity towards α1,3- and α1,4-fucosidic linkages. The members of a further subfamily have broader specificity, covering all α-fucosyl linkages. α-L-Fucosidases generally hydrolyse the terminal fucosyl residue from glycans. These enzymes are also capable to act as catalyst for fucosylation reaction due to their transfucosylation activity and thus may be used in the context of the method of the present invention, preferably under kinetically controlled conditions.

Fucosidases, which may be employed in the context of the present invention, may also comprise engineered fucosidases. Such engineered fucosidases preferably comprise engineered α-L-fucosidases, preferably engineered fucosidases derived from fucosidases as described above, e.g. an engineered α-1,2-L-fucosynthase from Bifidobacterium bifidum, α-L-fucosynthases from Sulfolobus solfataricus and Thermotoga maritime, etc. Such engineered fucosidases show an acceptor dependent regioselectivity and are devoid of product hydrolysis activity. Furthermore, engineered fucosidases preferably comprise α-L-fucosidase from Thermotoga maritime, which has also been recently converted into an efficient α-L-trans-fucosidase by directed evolution (see Osanjo, G., et al., Directed evolution of the alpha-L-fucosidase from Thermotoga maritima into an alpha-L-trans-fucosidase. Biochemistry, 2007, 46(4): p. 1022-33).

Even more preferably, the at least one enzyme having a fucosidase and/or trans-fucosidase activity may be selected from α-L-fucosidases derived from Thermotoga maritima MSB8, Sulfolobus solfataricus P2, Bifidobacterium bifidum JCM 1254, Bifidobacterium bifidum JCM 1254, Bifidobacterium longum subsp. infantis ATCC 15697, Bifidobacterium longum subsp. infantis ATCC 15697, Bifidobacterium longum subsp. Infantis JCM 1222, Bifidobacterium bifidum PRL2010, Bifidobacterium bifidum S17, Bifidobacterium longum subsp longum JDM 301, Bifidobacterium dentium Bd1, or Lactobacillus casei BL23, etc.

Even more preferably the at least one enzyme having a fucosidase and/or trans-fucosidase activity may be selected from following α-L-fucosidases as defined according to the following deposit numbers gi|4980806 (Thermotoga maritima MSB8, SEQ ID NO: 1), gi|13816464 (Sulfolobus solfataricus P2, SEQ ID NO: 2), gi|34451973 (Bifidobacterium bifidum JCM 1254, SEQ ID NO: 3), gi|242345155 (Bifidobacterium bifidum, JCM 1254, SEQ ID NO: 4), gi|213524647 (Bifidobacterium longum subsp. infantis, ATCC 15697, SEQ ID NO: 5), gi|213522629 (Bifidobacterium longum subsp. infantis ATCC 15697), gi|213522799 (Bifidobacterium longum subsp. infantis ATCC 15697), gi|213524646 (Bifidobacterium longum subsp. infantis ATCC 15697), gi|320457227 (Bifidobacterium longum subsp. infantis JCM 1222), gi|320457408 (Bifidobacterium longum subsp. infantis JCM 1222), gi|320459369 (Bifidobacterium longum subsp. infantis JCM 1222), gi|320459368 (Bifidobacterium longum subsp. infantis JCM 1222), gi|310867039 (Bifidobacterium bifidum PRL2010), gi|310865953 (Bifidobacterium bifidum PRL2010), gi|309250672 (Bifidobacterium bifidum S17), gi|309251774 (Bifidobacterium bifidum S17), gi|296182927 (Bifidobacterium longum subsp longum JDM 301), gi|296182928 (Bifidobacterium longum subsp longum JDM 301), gi|283103603 (Bifidobacterium dentium Bd1), gi|190713109 (Lactobacillus casei BL23, SEQ ID NO: 6), gi|190713871 (Lactobacillus casei BL23, SEQ ID NO: 7), gi|190713978 (Lactobacillus casei BL23, SEQ ID NO: 8), etc., or a sequence exhibiting a sequence identity with one of the above mentioned enzyme sequences having a fucosidase and/or trans-fucosidase activity of at least 70%, more preferably at least 80%, equally more preferably at least 85%, even more preferably at least 90% and most preferably at least 95% or even 97%, 98% or 99% as compared to the entire wild type sequence on amino acid level.

Particularly preferred α-L-fucosidases with fucosidase/trans-fucosidase activity are listed in the following Table 2:

TABLE 2 Preferred α-L-fucosidases GI number in SEQ ID GenBank Database Organisms NO: gi|4980806 Thermotoga maritima MSB8 1 gi|13816464 Sulfolobus solfataricus P2 2 gi|34451973 Bifidobacterium bifidum JCM 1254 3 gi|242345155 Bifidobacterium bifidum JCM 1254 4 gi|213524647 Bifidobacterium longum subsp. infantis ATCC 5 15697 gi|213522629 Bifidobacterium longum subsp. infantis ATCC — 15697 gi|213522799 Bifidobacterium longum subsp. infantis ATCC — 15697 gi|213524646 Bifidobacterium longum subsp. infantis ATCC — 15697 gi|320457227 Bifidobacterium longum subsp. infantis JCM — 1222 gi|320457408 Bifidobacterium longum subsp. infantis JCM — 1222 gi|320459369 Bifidobacterium longum subsp. infantis JCM — 1222 gi|320459368 Bifidobacterium longum subsp. infantis JCM — 1222 gi|310867039 Bifidobacterium bifidum PRL2010 — gi|310865953 Bifidobacterium bifidum PRL2010 — gi|309250672 Bifidobacterium bifidum S17 — gi|309251774 Bifidobacterium bifidum S17 — gi|296182927 Bifidobacterium longum subsp longum JDM 301 — gi|296182928 Bifidobacterium longum subsp longum JDM 301 — gi|283103603 Bifidobacterium dentium Bd1 — gi|190713109 Lactobacillus casei BL23 6 gi|190713871 Lactobacillus casei BL23 7 gi|190713978 Lactobacillus casei BL23 8

Likewise preferably, the at least one enzyme comprising a transglycosidase activity may be selected from an enzyme exhibiting a sialidase or trans-sialidase activity, preferably as described in the following. In this context, enzymes having a sialidase or trans-sialidase activity are preferably selected from a sialidase or trans-sialidase as described in the following, e.g. sialidases (EC 3.2.1.18) and trans-sialidases (EC 2.4.1.-) as classified according to the GH33 family. They are retaining enzymes. Sialidases and trans-sialidases are widely distributed in nature. They are found particularly in diverse virus families and bacteria, and also in protozoa, some invertebrates and mammalian. These enzymes differ in their biochemical properties, e.g., kinetics, binding affinity or substrate preference. Nevertheless, they possess conserved domains and structural similarities. Trans-sialidases differ from sialidases since can transfer sialic acids, preferably α-2,3-bonded sialic acids, from a donor molecule to an acceptor derivative, which is preferably a terminal galactose moiety with β-interglycosidic linkage. As a result of this transfer, an α-glycosidic bond is be formed between the sialic acid and the acceptor. However, if there is no suitable acceptor, the trans-sialidase hydrolyses the sialic acid.

The first trans-sialidase enzyme described was found in Trypanosoma cruzi, a protozoa which causes Chagas disease. This trans-sialidase (TcTS) has been extensively studied. Since that time trans-sialidases have been detected in several other trypanosome types such as Trypanosoma brucei gambiense, Trypanosoma brucei rhodesiense, Trypanosoma brucei brucei and Trypanosoma congolense. Moreover, the existence of trans-sialidases has been shown in Endotrypanum types, in Corynebacterium diphtheriae and even in the human plasma.

Sialidases can be classified into two different subgroups, endo- and exo-sialidases. The endo-sialidases hydrolyze sialic acid linkages internal to macromolecules, while the second, the exo-sialidases attack terminal sialic acid linkages, and desialylates glycoproteins, glycopeptides, gangliosides, oligosaccharides and polysaccharides. Recently, sialidases from Bifidobacterium bifidum and Bifidobacterium longum subsp. infantis have been identified, cloned and characterized. These sialidases can cleave and so recognize both α-2,3- and α-2,6-linked sialosides. Sialidases from Bifidobacterium longum subsp. infantis have a consistent preference for α-2,6-linkage whereas sialidases from Bifidobacterium bifidum have a consistent preference for α-2,3-linkage. These enzymes are also capable of acting as catalysts for sialylation reactions due to their trans-sialidase activity and thus may be used in the context of the method of the present invention, preferably under kinetically controlled conditions.

Sialidases, which may be employed in the context of the present invention, may also comprise engineered sialidases. Based on sequence and structure comparisons, sialidase from Trypanosoma rangeli may be mutated at six positions, wherein the resulting mutant is able to display a significant level of trans-sialidase activity (see Paris, G., et al., A sialidase mutant displaying trans-sialidase activity. J Mol Biol, 2005. 345(4): p. 923-34).

Even more preferably, the at least one enzyme having a sialidase and/or trans-sialidase activity may be selected from sialidases or trans-sialidases derived from Bifidobacterium longum subsp. infantis ATCC 15697, Bifidobacterium bifidum JCM1254, Bifidobacterium bifidum S17, Bifidobacterium bifidum PRL2010, Bifidobacterium bifidum NCIMB 41171, Trypanosoma cruzi, etc.

Even more preferably the at least one enzyme having a sialidase and/or trans-sialidase activity may be selected from sialidases or trans-sialidases as defined according to the following deposit numbers: gi|213524659 (Bifidobacterium longum subsp. infantis ATCC 15697, SEQ ID NO: 9), gi|213523006 Bifidobacterium longum subsp. infantis ATCC 15697, SEQ ID NO: 10), siab2 (Bifidobacterium bifidum JCM1254), further sialidases or trans-sialidases from Bifidobacterium bifidum JCM1254), gi|309252191 (Bifidobacterium bifidum S17, SEQ ID NO: 11), gi|309252190 (Bifidobacterium bifidum S17, SEQ ID NO: 12), gi|310867437 (Bifidobacterium bifidum PRL2010, SEQ ID NO: 13), gi|310867438 (Bifidobacterium bifidum PRL2010, SEQ ID NO: 14), gi|224283484 (Bifidobacterium bifidum NCIMB 41171), gi|313140638 (Bifidobacterium bifidum NCIMB 41171), gi|47252690 (Trypanosoma cruzi, SEQ ID NO: 15), gi|432485 (Trypanosoma cruzi, SEQ ID NO: 16), gi|343957998 (Trypanosoma congolense, SEQ ID NO:20), gi|343958004 (Trypanosoma congolense, SEQ ID NO:21) etc., or a sequence exhibiting a sequence identity with one of the above mentioned enzyme sequences having a sialidase and/or trans-sialidase activity of at least 70%, more preferably at least 80%, equally more preferably at least 85%, even more preferably at least 90% and most preferably at least 95% or even 97%, 98% or 99% as compared to the entire wild type sequence on amino acid level.

Particularly preferred sialidases with sialidase/trans-sialidase activity are listed in the following Table 3:

TABLE 3 Preferred sialidases/trans-sialidases GI number in GenBank SEQ Database Organisms ID NO: gi|213524659 Bifidobacterium longum subsp. infantis 9 ATCC 15697 gi|213523006 Bifidobacterium longum subsp. infantis 10 ATCC 15697 gi|309252191 Bifidobacterium bifidum S17 11 gi|309252190 Bifidobacterium bifidum S17 12 gi|310867437 Bifidobacterium bifidum PRL2010 13 gi|310867438 Bifidobacterium bifidum PRL2010 14 gi|224283484 Bifidobacterium bifidum NCIMB 41171 — gi|313140638 Bifidobacterium bifidum NCIMB 41171 — gi|47252690 Trypanosoma cruzi 15 gi|432485 Trypanosoma cruzi 16 gi|343957998 Trypanosoma congolense 20 gi|343958004 Trypanosoma congolense 21

Additionally, the at least one enzyme comprising a transglycosidase activity may be preferably selected from an enzyme exhibiting a lacto-N-biosidase or trans-lacto-N-biosidase activity, preferably as described in the following. In this context, enzymes having a lacto-N-biosidase or trans-lacto-N-biosidase activity are preferably selected from a lacto-N-biosidase or trans-lacto-N-biosidase as described in the following, e.g. lacto-N-biosidases (EC 3.2.1.140) as classified according to the GH20 family. Lacto-N-biosidases typically proceed through a retaining mechanism. Only two lacto-N-biosidases from Streptomyces and Bifidobacterium bifidum have been described and characterized up to now, which may be utilized in the present invention as a lacto-N-biosidase or trans-lacto-N-biosidase (see Sano, M., K. Hayakawa, and I. Kato, Proc Natl Acad Sci USA, 1992. 89(18): p. 8512-6; Sano, M., K. Hayakawa, and I. Kato, J Biol Chem, 1993. 268(25): p. 18560-6; Wada, J., et al., Appl Environ Microbiol, 2008. 74(13): p. 3996-4004.). Lacto-N-biosidases specifically hydrolyse the terminal lacto-N-biosyl residue (β-D-Gal-(1→3)-D-GlcNAc) from the non-reducing end of oligosaccharides with the structure β-D-Gal-(1→3)-β-D-GlcNAc-(1→3)-β-D-Gal-(1→R). Wada et al. (supra) and Murata et al. (Glycoconj. J. 16, 189 (1999)) also demonstrated the ability of the lacto-N-biosidase from Bifidobacterium bifidum and Aureobacterium sp. L-101, respectively, to catalyze the transglycosylation by incubating donor substrates (such as lacto-N-tetraose and pNP-β-LNB) with acceptors (such as various 1-alkanols and lactose).

Even more preferably, the at least one enzyme having a lacto-N-biosidase or trans-lacto-N-biosidase activity may be selected from lacto-N-biosidases or trans-lacto-N-biosidases derived from Bifidobacterium bifidum JCM1254, Bifidobacterium bifidum PRL2010, Bifidobacterium bifidum NCIMB 41171, Aureobacterium sp. L-101 or Streptomyces sp., etc.

Even more preferably the at least one enzyme having a lacto-N-biosidase or trans-lacto-N-biosidase activity may be selected from lacto-N-biosidases or trans-lacto-N-biosidases as defined according to the following deposit numbers: gi|167369738 (Bifidobacterium bifidum JCM1254, SEQ ID NO: 17), gi|4096812 (Streptomyces sp., SEQ ID NO: 18), gi|310867103 (Bifidobacterium bifidum PRL2010), gi|313140985 (Bifidobacterium bifidum NCIMB 41171), etc., or a sequence exhibiting a sequence identity with one of the above mentioned enzyme sequences having a lacto-N-biosidase or trans-lacto-N-biosidase activity of at least 70%, more preferably at least 80%, equally more preferably at least 85%, even more preferably at least 90% and most preferably at least 95% or even 97%, 98% or 99% as compared to the entire wild type sequence on amino acid level.

Particularly preferred lacto-N-biosidases with lacto-N-biosidase or trans-lacto-N-biosidase activity are listed in the following Table 4:

TABLE 4 Preferred lacto-N-biosidases or trans-lacto-N-biosidases GI number in SEQ GenBank Database Organisms ID NO: gi|167369738 Bifidobacterium bifidum JCM1254 17 gi|4096812 Streptomyces sp. 18 gi|310867103 Bifidobacterium bifidum PRL2010 — gi|313140985 Bifidobacterium bifidum NCIMB 41171 —

Furthermore, the at least one enzyme comprising a transglycosidase activity may be preferably selected from an enzyme exhibiting a N-acetyllactosaminidase or trans-N-acetyllactosaminidase activity, preferably as described in the following. In this context, enzymes having a N-acetyllactosaminidase or trans-N-acetyllactosaminidase activity are preferably selected from a N-acetyllactosaminidase or trans-N-acetyllactosaminidase as described in the following, e.g. lacto-N-biosidases (EC 3.2.1.140) as classified according to the GH20 family. Particularly preferably, chitinase from bacillus circulans, more preferably chitinase A1 from Bacillus Circulans WL-12 as deposited under gi|142688 (SEQ ID NO: 19), may be used as a N-acetyllactosaminidase or trans-N-acetyllactosaminidase, or a sequence exhibiting a sequence identity with one of the above mentioned enzyme sequences having a N-acetyllactosaminidase or trans-N-acetyllactosaminidase activity of at least 70%, more preferably at least 80%, equally more preferably at least 85%, even more preferably at least 90% and most preferably at least 95% or even 97%, 98% or 99% as compared to the entire wild type sequence on amino acid level. Notably, Shoda et al. showed that chitinase A1 from B. Circulans WL-12 is able to transfer N-acetyllactosamine with a β-1,6 glycosidic linkage using 1,2-oxazoline derivative of transfer N-acetyllactosamine (see Shoda, S.-i., et al., Cellulose, 2006. 13(4): p. 477-484.).

Particularly preferred N-acetyllactosaminidases or trans-N-acetyllactosaminidases are listed in the following Table 5:

TABLE 5 Preferred N-acetyllactosaminidases or trans-N-acetyllactosaminidases GI number in the GenBank Database Organisms SEQ ID NO: gi|142688 Bacillus circulans 19

As defined above, proteins comprising a transglycosidase as defined above may also comprise engineered proteins comprising a transglycosidase activity. It is particularly envisaged that wild type or mutated glycosidases displaying a transfucosidase, transsialidase, trans-lacto-N-biosidase and/or trans-N-acetyllactosaminidase activity, preferably a α-transfucosidase, α-transsialidase, β-trans-lacto-N-biosidase and/or β-trans-N-acetyllactosaminidase activity, can be used in the present invention to produce such oligosaccharides. Preparation of such enzymes is preferably carried out via site directed mutagenesis approaches or directed evolution.

In rational engineering novel altered enzymes (mutants) are created via site directed mutagenesis approaches, preferably by introduction of point mutations. This technique generally requires reliance on the static 3D protein structure. The mutations generally affect the active site of the enzymes such that they lose their ability to degrade their transglycosylation products but remain capable of synthesis. A preferred strategy consists of the replacement of the catalytic nucleophile by a non-nucleophilic residue. This modification results in the formation of an inactive mutant or an altered enzyme with reduced transglycosylation activity due the lack of appropriate environment for the formation of the reactive host-guest complex for transglycosylation. However, in the presence of more active glycosyl donor (e.g. glycosyl fluoride) that mimics the glycosyl enzyme intermediate the mutated enzyme is able to transfer efficiently the glycosyl moiety to a suitable acceptor generating a glycoside with inverted anomeric stereochemistry.

The second preferred technique is called directed evolution. This strategy comprises random mutagenesis applied on the gene of the selected glycosidase and generates thus a library of genetically diverse genes expressing glycosidase. Generation of sequence diversity can be performed using well-known methodologies, the most preferable being the error prone polymerase chain reaction (epCR) method. This gene library may be inserted into suitable microorganisms such as E. coli or S. cerevisiae for producing recombinant variants with slightly altered properties. Clones expressing improved enzymes are then identified with a fast and reliable screening method, selected and brought into a next round of mutation process. The recursive cycles of mutation, recombination and selection are continued as far as mutant(s) with the desired activity and/or specificity is/are evolved. To date, different high-throughput screening methodologies for glycosidases have been developed. Applying these approaches, performant engineered transglycosidases can and have been created and isolated. An α-L-fucosidase from Thermotoga maritima has been recently converted into an efficient α-L-transfucosidase by directed evolution. The transferase/hydrolysis ratio of the evolved enzyme was 30 times higher than the native enzyme (see Osanjo, G., et al., Biochemistry, 2007. 46(4): p. 1022-33).

Proteins comprising a transglycosidase activity as defined above may also comprise fragments or variants of those protein sequences. Such fragments or variants may typically comprise a sequence having a sequence identity with one of the above mentioned proteins sequences of at least 70%, more preferably at least 80%, equally more preferably at least 85%, even more preferably at least 90% and most preferably at least 95% or even 97%, 98% or 99% as compared to the entire wild type sequence on amino acid level.

“Fragments” of proteins or peptides in the context of the present invention may also comprise a sequence of a protein or peptide as defined herein, which is, with regard to its amino acid sequence N-terminally, C-terminally and/or intrasequentially truncated compared to the amino acid sequence of the original (native) protein. Such truncation may thus occur either on the amino acid level or correspondingly on the nucleic acid level. A sequence identity with respect to such a fragment as defined herein may therefore preferably refer to the entire protein or peptide as defined herein or to the entire (coding) nucleic acid molecule of such a protein or peptide. Likewise, “fragments” of nucleic acids in the context of the present invention may comprise a sequence of a nucleic acid as defined herein, which is, with regard to its nucleic acid molecule 5′-, 3′- and/or intrasequentially truncated compared to the nucleic acid molecule of the original (native) nucleic acid molecule. A sequence identity with respect to such a fragment as defined herein may therefore preferably refer to the entire nucleic acid as defined herein.

“Variants” of proteins or peptides as defined in the context of the present invention (e.g. as encoded by a nucleic acid as defined herein) may be encoded by the nucleic acid molecule of the inventive polymeric carrier cargo complex. Thereby, a protein or peptide may be generated, having an amino acid sequence which differs from the original sequence in one or more mutation(s), such as one or more substituted, inserted and/or deleted amino acid(s). Preferably, these fragments and/or variants have the same biological function or specific activity compared to the full-length native protein, e.g. its specific antigenic property.

“Variants” of proteins or peptides as defined in the context of the present invention (e.g. as encoded by a nucleic acid as defined herein) may also comprise conservative amino acid substitution(s) compared to their native, i.e. non-mutated physiological, sequence. Those amino acid sequences as well as their encoding nucleotide sequences in particular fall under the term variants as defined herein. Substitutions in which amino acids, which originate from the same class, are exchanged for one another are called conservative substitutions. In particular, these are amino acids having aliphatic side chains, positively or negatively charged side chains, aromatic groups in the side chains or amino acids, the side chains of which can enter into hydrogen bridges, e.g. side chains which have a hydroxyl function. This means that e.g. an amino acid having a polar side chain is replaced by another amino acid having a likewise polar side chain, or, for example, an amino acid characterized by a hydrophobic side chain is substituted by another amino acid having a likewise hydrophobic side chain (e.g. serine (threonine) by threonine (serine) or leucine (isoleucine) by isoleucine (leucine)). Insertions and substitutions are possible, in particular, at those sequence positions which cause no modification to the three-dimensional structure or do not affect the binding region. Modifications to a three-dimensional structure by insertion(s) or deletion(s) can easily be determined e.g. using CD spectra (circular dichroism spectra) (Urry, 1985, Absorption, Circular Dichroism and ORD of Polypeptides, in: Modem Physical Methods in Biochemistry, Neuberger et al. (ed.), Elsevier, Amsterdam).

Furthermore, variants of proteins or peptides as defined herein may also comprise those sequences, wherein nucleotides of the nucleic acid are exchanged according to the degeneration of the genetic code, without leading to an alteration of the respective amino acid sequence of the protein or peptide, i.e. the amino acid sequence or at least part thereof may not differ from the original sequence in one or more mutation(s) within the above meaning.

In order to determine the percentage to which two sequences are identical, e.g. nucleic acid sequences or amino acid sequences as defined herein, preferably the amino acid sequences encoded by a nucleic acid sequence of the polymeric carrier as defined herein or the amino acid sequences them selves, the sequences can be aligned in order to be subsequently compared to one another. Therefore, e.g. a position of a first sequence may be compared with the corresponding position of the second sequence. If a position in the first sequence is occupied by the same component as is the case at a position in the second sequence, the two sequences are identical at this position. If this is not the case, the sequences differ at this position. If insertions occur in the second sequence in comparison to the first sequence, gaps can be inserted into the first sequence to allow a further alignment. If deletions occur in the second sequence in comparison to the first sequence, gaps can be inserted into the second sequence to allow a further alignment. The percentage to which two sequences are identical is then a function of the number of identical positions divided by the total number of positions including those positions which are only occupied in one sequence. The percentage to which two sequences are identical can be determined using a mathematical algorithm. A preferred, but not limiting, example of a mathematical algorithm which can be used is the algorithm of Karlin et al. (1993), PNAS USA, 90:5873-5877 or Altschul et al. (1997), Nucleic Acids Res., 25:3389-3402. Such an algorithm is integrated in the BLAST program. Sequences which are identical to the sequences of the present invention to a certain extent can be identified by this program.

The proteins as added in step b) of the first aspect, including the preferred and more preferred embodiments, may be provided in a free form or alternatively be bound to or are immobilized onto a surface. In this specific case, the order of steps a) and b) is preferably inverted. Binding to or immobilization onto a surface may be carried out e.g. via electrostatic bonds, van der Waals-bonds, covalent bonds, etc. Binding to or immobilization onto a surface may be furthermore carried out, using a covalent linker or a crosslinker, or a Tag, as known to a skilled person for purification of proteins. Such tags comprise, inter alia, e.g. affinity tags or chromatography tags. Affinity tags may include e.g. chitin binding protein (CBP), maltose binding protein (MBP), glutathione-S-transferase (GST), or the Strep-Tag. The poly(His) tag is a widely-used protein tag, that binds to metal matrices. Chromatography tags are used to alter chromatographic properties of the protein to afford different resolution across a particular separation technique, and include e.g. polyanionic amino acids based tags, such as the FLAG-tag. The surface may be the surface of a bioreactor, or any suitable reaction chamber.

In a further step c) of the first aspect, including the preferred and more preferred embodiments, for diversification of human milk oligosaccharides (HMOs), the mixture containing at least one compound as defined according to step a) or a mixture thereof and at least one enzyme as added according to step b) are preferably incubated to allow diversification of human milk oligosaccharides (HMOs) or derivatives thereof via enzymatic means using the at least one enzyme comprising a transglycosidase activity as defined herein.

Incubation according to step c) of the first aspect, including the preferred and more preferred embodiments, preferably occurs with a concentration of (each of the) enzymes in a concentration of 1 mU/l to 1,000 U/l, preferably 10 mU/l to 100 U/l, when the activity capable of forming 1 μmol of specific product for a defined protein starting from a defined educt is defined as 1 unit (U), e.g. for a glycotransferase the production of a glycose-containing complex carbohydrate at 37° C. in 1 minute. The activity of each enzyme as defined herein may be assessed with respect to its naturally occurring or engineered substrate accordingly.

The incubation according to step c) of the first aspect, including the preferred and more preferred embodiments, may be carried out in a reaction medium, preferably an aqueous medium, comprising the mixture obtained according to step b) and optionally water; a buffer such as a phosphate buffer, a carbonate buffer, an acetate buffer, a borate buffer, a citrate buffer and a TRIS buffer, or combinations thereof, alcohol, such as methanol and ethanol; ester such as ethyl acetate; ketone such as acetone; amide such as acetamide; and the like.

Furthermore, the incubation according to step c) of the first aspect, including the preferred and more preferred embodiments, may be carried out in a reaction medium as defined above, wherein optionally a surfactant or an organic solvent may be added, if necessary. Any surfactant capable of accelerating the formation of a complex carbohydrate as defined according to the present invention as a possible product of the invention can be used as the surfactant. Examples include nonionic surfactants such as polyoxyethylene octadecylamine (e.g., Nymeen S-215, manufactured by Nippon Oil & Fats); cationic surfactants, such as cetyltrimethylammonium bromide and alkyldimethyl benzylammoniumchloride (e.g., Cation F2-40E, manufactured by Nippon Oil & Fats); anionic surfactants such as lauroyl sarcosinate; tertiary amines such as alkyldimethylamine (e.g., Tertiary Amine FB, manufactured by Nippon Oil & Fats); and the like, which are used alone or as a mixture of two or more. The surfactant may be used generally in a concentration of 0.1 to 50 g/l. The organic solvent may include xylene, toluene, fatty acid alcohol, acetone, ethyl acetate, and the like, which may be used in a concentration of generally 0.1 to 50 ml/l.

The incubation according to step c) of the first aspect, including the preferred and more preferred embodiments, may be furthermore carried out in a reaction medium as defined above, preferably having a pH 3 to 10, pH 5 to 10, preferably pH 6 to 8.

The incubation according to step c) of the first aspect, including the preferred and more preferred embodiments, may be furthermore carried out at a temperature of about 0° C. to about 100° C., preferably at a temperature of about 10 to about 50° C., e.g. at a temperature of about 20° C. to about 50° C. In the reaction medium, inorganic salts, such as MnCl₂ and MgCl₂, may be added, if necessary.

The incubation according to step c) of the first aspect, including the preferred and more preferred embodiments, may be carried out in a bioreactor. The bioreactor is preferably suitable for either a continuous mode or a discontinuous mode.

The incubation according to step c) of the first aspect, including the preferred and more preferred embodiments, may be carried out in a continuous or discontinuous manner. If carried out in a continuous manner, the method preferably provides for a continuous flow of compounds and/or enzymes as necessary, preferably by continuously providing educts of the reaction to the reaction mixture and continuously removing products from the reaction mixture, while maintaining the concentration of all components, including enzymes at a predetermined level. The enzymes used in a continuous mode may be added either in free form or as bound or immobilized to a surface.

With regard to the first aspect of the present invention, at least steps a) and c) or steps b) and c) may be repeated with the mixture obtained according to step c) according to an optional step d). This mixture has already been incubated and thus processed with at least one compound as defined herein for step a) and at least one enzyme as defined herein according to step b). Such a stepwise proceeding may allow within multiple rounds the rational diversification of a defined set of educts to a limited set of compounds in a controllable manner. Adding specific compounds as defined according to step a) and different proteins as defined according to step b) in a predetermined order may also provide for a rational exclusion of specific components. To obtain such a variety, the compounds and/or enzymes may be added simultaneously or sequentially, and preferably compounds and/or enzymes may be added simultaneously in one step and/or sequentially in different steps.

Alternatively, a compound or a mixture of compounds as defined herein for step a) and at least one enzyme as defined herein according to step b) may be incubated in one step, preferably wherein all compounds are provided simultaneously. Such a proceeding may be preferred in certain circumstances, as it may lead to the largest variety of diversified compounds.

With regard to the preferred embodiment of the first aspect, at least one more additional incubation cycle d) is needed when both: only two compounds are provided in step a) of the first cycle, of which one is 3′-sialyllactose, and the enzyme provided in step b) of the first cycle is an enzyme comprising a trans-sialidase activity. Particularly preferably, at least steps a) and c) or steps b) and c) shall be repeated, with the mixture obtained according to step c). When repeating steps a) and c), the at least one compound added according to step a) is preferably different from that/those provided in the first cycle; and, when repeating steps b) and c), the at least one enzyme added according to step b) is preferably different from that provided in the first cycle. When repeating all of steps a) to c), suitably either the at least one compound provided in step a) or the at least one enzyme provided in step b) are different from those provided in the first cycle, and preferably both are different from those provided in the first cycle.

With regard to the preferred embodiment of the first aspect, at least one more additional incubation cycle d) is needed when both: only two compounds are provided in step a) of the first cycle, of which one is sialylated lactose derivative of general formula 2 or 4, and the enzyme provided in step b) of the first cycle is an enzyme comprising a trans-sialidase activity. Particularly preferably, at least steps a) and c) or steps b) and c) shall be repeated, with the mixture obtained according to step c). When repeating step a) and c), the at least one compound added according to step a) is preferably different from that/those provided in the first cycle; when repeating step b) and c), the at least one enzyme added according to step b) is preferably different from that provided in the first cycle. When repeating all of steps a) to c), suitably either the at least one compound provided in step a) or the at least one enzyme provided in step b) are different from those provided in the first cycle, and preferably both are different from those provided in the first cycle.

With regard to the preferred embodiment of the first aspect, at least one more additional incubation cycle d) is needed when both: only two compounds are provided in step a) of the first cycle, of which one is a fucosylated lactose derivative of general formula 2 or 4, and the enzyme provided in step b) of the first cycle is an enzyme comprising a trans-fucosidase activity. Particularly preferably, at least steps a) and c) or steps b) and c) shall be repeated, with the mixture obtained according to step c). When repeating step a) and c), the at least one compound added according to step a) is preferably different from that/those provided in the first cycle; when repeating step b) and c), the at least one enzyme added according to step b) is preferably different from that provided in the first cycle. When repeating all of steps a) to c), suitably either the at least one compound provided in step a) or the at least one enzyme provided in step b) are different from those provided in the first cycle, and preferably both are different from those provided in the first cycle.

Furthermore, with regard to the preferred embodiment of the first aspect at least steps a) and c) or steps b) and c) may be repeated with the mixture obtained according to step c) according to an optional step e). Preferably, this mixture has already been incubated and thus processed with at least one compound as defined herein for step a) and at least one enzyme as defined herein according to step b). Such a stepwise proceeding may allow within multiple rounds the rational diversification of a defined set of educts to a limited set of compounds in a controllable manner. Adding specific compounds as defined according to step a) and different proteins as defined according to step b) in a predetermined order may also provide for a rational exclusion of specific components. To obtain such a variety, the compounds and/or enzymes may be added simultaneously or sequentially, more preferably compounds and/or enzymes may be added simultaneously in one step and/or sequentially in different steps.

Alternatively, a compound or a mixture of compounds as defined herein for step a) and at least one enzyme as defined herein according to step b) may be incubated in one step, preferably wherein all compounds are provided simultaneously. Such a proceeding may be preferred in certain circumstances, as it may lead to the largest variety of diversified compounds.

With regard to the more preferred embodiment of the first aspect, at least one more additional incubation cycle d) is needed when only one product (HMO or HMO derivative or HMO precursor) is formed after the first incubation cycle. This includes the situation wherein the mixture obtained after the first incubation step c) comprised starting material(s) from the first step a) as well as one HMO or HMO derivative or HMO precursor as the product of the reaction of the starting material(s) with the at least one enzyme. Particularly preferably, at least steps a) and c) or steps b) and c) are repeated with the mixture obtained according to step c). When repeating the steps a) and c), the at least one compound added according to step a) is preferably different from that/those provided in the first cycle; and when repeating steps b) and c) the at least one enzyme added according to step b) is preferably different from that provided in the first cycle. When repeating all of steps a) to c), suitably either the at least one compound provided in step a) or the at least one enzyme provided in step b) are different from those provided in the first cycle, and preferably both are different from those provided in the first cycle.

A person skilled in the art is able to explore and decide whether only one HMO or HMO derivative or precursor thereof is made after the first incubation step and whether at least one more incubation cycle is needed to achieve the goal. In a possible case, the selection of a particular donor, a particular acceptor and a particular enzyme leads to only one product. When more than one donor and/or more than one acceptor and/or more than one enzyme are used for generating HMOs, HMO derivatives or HMO precursors in one incubation cycle, more than one product is generally expected to be formed. Similarly, when the glycosidase and/or glycosynthase enzyme used has lesser (regio)selectivity, more product can be expected, even if only one acceptor is provided, as the enzyme is able to transfer the glycosyl moiety to various parts of the acceptor. Moreover, according to a general rule the proportion of the donor and acceptor can have a huge impact on the product diversity: the higher the donor-acceptor ratio, the higher the chance of obtaining more than one product in a one donor-one acceptor system. The skilled person has the repertoire of detection and monitoring methods, both qualitative and quantitative (e.g. TLC, HPLC, GC, GC-MS, electrophoresis, etc.) to find out whether one or more products have been formed.

Furthermore, with regard to the more preferred embodiment of the first aspect at least steps a) and c) or steps b) and c) may be repeated with the mixture obtained according to step c) according to an optional step e). Preferably, this mixture has already been incubated and thus processed with at least one compound as defined herein for step a) and at least one enzyme as defined herein according to step b). Such a proceeding may allow within multiple rounds the rational diversification of a defined set of educts to a limited set of compounds in a controllable manner. Adding specific compounds as defined according to step a) and different proteins as defined according to step b) in a predetermined order may also provide for a rational exclusion of specific components. To obtain such a variety, the compounds and/or enzymes may be added simultaneously or sequentially, more preferably compounds and/or enzymes may be added simultaneously in one step and/or sequentially in different steps.

Alternatively, a compound or a mixture of compounds as defined herein for step a) and at least one enzyme as defined herein according to step b) may be incubated in one step, preferably wherein all compounds are provided simultaneously. Such a proceeding may be preferred in certain circumstances, as it may lead to the largest variety of diversified compounds.

The method of the present invention as defined above leads to diversification of the compounds as provided in step a) after incubation step c) of any embodiment of the first aspect, or preferably the compulsory or optional repetition of steps according to step d) or e) of any embodiment of the first aspect. Preferably, the method of the present invention as described herein results in either a single human milk oligosaccharide (HMO) or a derivative thereof, as defined below, or a diversified mixture comprising two or more human milk oligosaccharides (HMOs) or derivatives thereof, the single compounds of which may be defined according to

-   -   compounds of general formula 1 and salts thereof:

-   -   wherein     -   R is a group removable by hydrogenolysis,     -   R₁ is fucosyl or H,     -   R₂ is selected from N-acetyl-lactosaminyl and lacto-N-biosyl         groups, wherein the N-acetyl lactosaminyl group may carry a         glycosyl residue comprising one or more N-acetyl-lactosaminyl         and/or one or more lacto-N-biosyl groups; any         N-acetyl-lactosaminyl and lacto-N-biosyl group can be         substituted with one or more sialyl and/or fucosyl residue,     -   R₃ is H or N-acetyl-lactosaminyl group optionally substituted         with a glycosyl residue comprising one or more         N-acetyl-lactosaminyl and/or one or more lacto-N-biosyl groups;         any N-acetyl-lactosaminyl and lacto-N-biosyl group can be         substituted with one or more sialyl and/or fucosyl residue;     -   compounds of general formula 2 and salts thereof

-   -   wherein     -   R is a group removable by hydrogenolysis,     -   R₁ independently of each other is fucosyl or H     -   R₄ independently of each other is sialyl or H,     -   with the proviso that at least one R₁ or R₄ is not H,     -   compounds of general formula 3 and salts thereof

-   -   -   wherein         -   R₁ is fucosyl or H,         -   R₂ is selected from N-acetyl-lactosaminyl and lacto-N-biosyl             groups, wherein the N-acetyl lactosaminyl group may carry a             glycosyl residue comprising one or more             N-acetyl-lactosaminyl and/or one or more lacto-N-biosyl             groups; any N-acetyl-lactosaminyl and lacto-N-biosyl group             can be substituted with one or more sialyl and/or fucosyl             residue,         -   R₃ is H or N-acetyl-lactosaminyl group optionally             substituted with a glycosyl residue comprising one or more             N-acetyl-lactosaminyl and/or one or more lacto-N-biosyl             groups; any N-acetyl-lactosaminyl and lacto-N-biosyl group             can be substituted with one or more sialyl and/or fucosyl             residue; and/or         -   compounds of general formula 4 and salts thereof

-   -   -   wherein         -   R₁ independently of each other is fucosyl or H         -   R₄ independently of each other is sialyl or H,         -   with the proviso that at least one R₁ or R₄ is not H.

Even more preferably, the method of the present invention for diversification of human milk oligosaccharides (HMOs) results in either single human milk oligosaccharide derivatives, or a diversified mixture comprising two or more human milk oligosaccharide (HMO) derivatives, as defined above, after incubation step c) of any embodiment of the first aspect, or the compulsory or optional repetition of steps according to step d) or e) of any embodiment of the first aspect, wherein compounds of formulae 1 and 2 are further characterized by general formulae 1a, 1b or 2 and salts thereof

-   -   wherein     -   R, R₁ and R₄ are as defined above,     -   R_(2a) is an N-acetyl-lactosaminyl group optionally substituted         with a glycosyl residue comprising one N-acetyl-lactosaminyl         and/or one lacto-N-biosyl group; any N-acetyl-lactosaminyl and         lacto-N-biosyl group can be substituted with one or more sialyl         and/or fucosyl residue,     -   R_(3a) is H or an N-acetyl-lactosaminyl group optionally         substituted with a lacto-N-biosyl group; any         N-acetyl-lactosaminyl and lacto-N-biosyl group can be         substituted with one or more sialyl and/or fucosyl residue,     -   R_(2b) is a lacto-N-biosyl group optionally substituted with         sialyl and/or fucosyl residue, and     -   R_(3b) is H or an N-acetyl-lactosaminyl group optionally         substituted with one or two N-acetyl-lactosaminyl and/or one         lacto-N-biosyl group; any N-acetyl-lactosaminyl and         lacto-N-biosyl group can be substituted with one or more sialyl         and/or fucosyl residue.

Particularly preferably, compounds obtained according to the method of the present invention for diversification as defined above are characterized by their linkages and modifications. Preferably, the compounds obtained by the method of the present inventionafter incubation step c) of any embodiment of the first aspect, or a compulsory or optional repetition of steps according to step d) or e) of any embodiment of the first aspect, and preferably as defined according to general formulae 1a and 1b, are characterized in that:

-   -   the N-acetyl-lactosaminyl group in the glycosyl residue of         R_(2a) in general formula 1a is attached to the another         N-acetyl-lactosaminyl group by a 1-3 interglycosidic linkage,     -   the lacto-N-biosyl group in the glycosyl residue of R_(2a) in         general formula 1a is attached to the N-acetyl-lactosaminyl         group by a 1-3 interglycosidic linkage,     -   the lacto-N-biosyl group in the glycosyl residue of R_(3a) in         general formula 1a is attached to the N-acetyl-lactosaminyl         group by a 1-3 interglycosidic linkage,     -   the N-acetyl-lactosaminyl group in the glycosyl residue of         R_(3b) in general formula 1b is attached to another         N-acetyl-lactosaminyl group by a 1-3 or 1-6 interglycosidic         linkage,     -   the lacto-N-biosyl group in the glycosyl residue of R_(3b) in         general formula 1b is attached to the N-acetyl-lactosaminyl         group by a 1-3 interglycosidic linkage.

Preferably, the compounds obtained by the method of the present invention after incubation step c) of any embodiment of the first aspect, or a compulsory or optional repetition of steps according to step d) or e) of any embodiment of the first aspect, are characterized in that general formula 1a represents the R-glycosides of lacto-N-neotetraose, para-lacto-N-hexaose, para-lacto-N-neohexaose, lacto-N-neohexaose, para-lacto-N-octaose and lacto-N-neooctaose optionally substituted with one or more sialyl and/or fucosyl residue, and general formula 1b represents the R-glycosides of lacto-N-tetraose, lacto-N-hexaose, lacto-N-octaose, iso-lacto-N-octaose, lacto-N-decaose and lacto-N-neodecaose optionally substituted with one or more sialyl and/or fucosyl residue.

Preferably, the compounds obtained by the method of the present invention, after incubation step c) and/or a repetition of steps according to step d) or e), are characterized in that:

-   -   the fucosyl residue attached to the N-acetyl-lactosaminyl and/or         the lacto-N-biosyl group is linked to         -   the galactose of the lacto-N-biosyl group with a 1-2             interglycosidic linkage and/or         -   the N-acetyl-glucosamine of the lacto-N-biosyl group with a             1-4 interglycosidic linkage and/or         -   the N-acetyl-glucosamine of the N-acetyl-lactosaminyl group             with a 1-3 interglycosidic linkage,     -   the sialyl residue attached to the N-acetyl-lactosaminyl and/or         the lacto-N-biosyl group is linked to         -   the galactose of the lacto-N-biosyl group with a 2-3             interglycosidic linkage and/or         -   the N-acetyl-glucosamine of the lacto-N-biosyl group with a             2-6 interglycosidic linkage and/or         -   the galactose of the N-acetyl-lactosaminyl group with a 2-6             interglycosidic linkage.

According to a further preferred aspect, compounds as obtained according to the method of the present invention of diversification, preferably compounds according to formulae 1 or 2 or of general subformulae 1a, 1b or 2 may be selected from the group of: R-glycosides of 2′-fucosyllactose, 3-fucosyllactose, 2′,3-difucosyllactose, 3′-sialyllactose, 6′-sialyllactose, 3′-sialyl-3-fucosyllactose, lacto-N-tetraose, lacto-N-neotetraose, LNFP-I, LNFP-II, LNFP-III, LNFP-V, LST-a, LST-b, LST-c, FLST-a, FLST-b, FLST-c, LNDFH-I, LNDFH-II, LNDFH-III, DS-LNT, FDS-LNT I and FDS-LNT II, or salts thereof. The core structures of these compounds are shown in Table 6 below. The R-glycosides may be alpha or beta-anomers. Preferably, said R-glycosides are the beta-anomers.

TABLE 6 Core structures of R-glycosides of naturally occuring HMOs having a lactose, LNT or LNnT core Abbreviation Chemical Structure 2′-FL Fuc(α1-2)Gal(β1-4)Glc 3-FL

DFL

3′-SL Neu5Ac(α2-3)Gal(β1-4)Glc FSL

LNT Gal(β1-3)GlcNAc(β1-3)Gal(β1-4)Glc LNFP I Fuc(α1-2)Gal(β1-3)GlcNAc(β1-3)Gal(β1-4)Glc LNFP II

LNFP III

LNFP V

LNDFH I

LNDFH II

LNDFH III

LSTa Neu5Ac(α2-3)Gal(β1-3)GlcNAc(β1-3)Gal(β1-4)Glc LSTb

LSTc Neu5Ac(α2-6)Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)Glc F-LSTa

F-LSTb

F-LSTc

DS-LNT

FDS-LNT I

FDS-LNT II

LNnT Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)Glc

Most preferably, compounds as obtained according to the method of diversification of the present invention, preferably compounds according to formulae 1 or 2 or of general subformulae 1a, 1b or 2 may be selected from compounds wherein R is benzyl.

According to a further specific aspect of the method of the present invention the compounds obtained according to the method of the present invention, preferably compounds according to any of formulae 1 or 2 or of general subformulae 1a, 1b or 2 are optionally subjected to a hydrogenolysis reaction subsequent to incubation according to step c) and/or a further repetition according to step d) or e), resulting in the formation of HMOs characterized by general formulae 3 and 4 defined above.

Likewise preferably, the method for diversification of human milk oligosaccharides (HMOs) of the present invention results in human milk oligosaccharides as defined above, after incubation step c) and optionally a repetition of steps according to step d) or e), wherein compounds of formulae 3 and 4 are further characterized by general formulae 3a, 3b or 4 and salts thereof

wherein R₁ and R₄ are as defined above,

R_(2a) is an N-acetyl-lactosaminyl group optionally substituted with a glycosyl residue comprising one N-acetyl-lactosaminyl and/or one lacto-N-biosyl group; any N-acetyl-lactosaminyl and/or lacto-N-biosyl group can be substituted with one or more sialyl and/or fucosyl residue,

R_(3a) is H or an N-acetyl-lactosaminyl group optionally substituted with a lacto-N-biosyl group; any N-acetyl-lactosaminyl and/or lacto-N-biosyl group can be substituted with one or more sialyl and/or fucosyl residue,

R_(2b) is a lacto-N-biosyl group optionally substituted with sialyl and/or fucosyl residue(s),

R_(3b) is H or an N-acetyl-lactosaminyl group optionally substituted with one or two N-acetyl-lactosaminyl and/or one lacto-N-biosyl group; any N-acetyl-lactosaminyl and/or lacto-N-biosyl group can be substituted with one or more sialyl and/or fucosyl residue.

Particularly preferably, compounds obtained according to the method of the present invention for diversification as defined above are characterized by their linkages and modifications. Preferably, the compounds obtained by the method of the present invention, after incubation step c) and optionally a repetition of steps according to step d) or e), and as preferably defined according to general formulae 3a or 3b, are characterized in that:

-   -   the N-acetyl-lactosaminyl group in the glycosyl residue of         R_(2a) in general formula 3a is attached to the another         N-acetyl-lactosaminyl group by a 1-3 interglycosidic linkage,     -   the lacto-N-biosyl group in the glycosyl residue of R_(2a) in         general formula 3a is attached to the N-acetyl-lactosaminyl         group by a 1-3 interglycosidic linkage,     -   the lacto-N-biosyl group in the glycosyl residue of R_(3a) in         general formula 3a is attached to the N-acetyl-lactosaminyl         group by a 1-3 interglycosidic linkage,     -   the N-acetyl-lactosaminyl group in the glycosyl residue of         R_(3b) in general formula 3b is attached to another         N-acetyl-lactosaminyl group by a 1-3 or 1-6 interglycosidic         linkage,     -   the lacto-N-biosyl group in the glycosyl residue of R_(3b) in         general formula 3b is attached to the N-acetyl-lactosaminyl         group by a 1-3 interglycosidic linkage.

Preferably, the compounds obtained by the method of the present invention, after incubation step c) and optionally a repetition of steps according to step d) or e), are characterized in that general formula 3a represents lacto-N-neotetraose, para-lacto-N-hexaose, para-lacto-N-neohexaose, lacto-N-neohexaose, para-lacto-N-octaose and lacto-N-neooctaose optionally substituted with one or more sialyl and/or fucosyl residue, and general formula 3b represents lacto-N-tetraose, lacto-N-hexaose, lacto-N-octaose, iso-lacto-N-octaose, lacto-N-decaose and lacto-N-neodecaose optionally substituted with one or more sialyl and/or fucosyl residue.

Preferably, the compounds obtained by the method of the present invention, after incubation step c) and/or a repetition of steps according to step d) or e), are characterized in that:

-   -   the fucosyl residue attached to the N-acetyl-lactosaminyl and/or         the lacto-N-biosyl group is linked to         -   the galactose of the lacto-N-biosyl group with a 1-2             interglycosidic linkage and/or         -   the N-acetyl-glucosamine of the lacto-N-biosyl group with a             1-4 interglycosidic linkage and/or         -   the N-acetyl-glucosamine of the N-acetyl-lactosaminyl group             with a 1-3 interglycosidic linkage,     -   the sialyl residue attached to the N-acetyl-lactosaminyl and/or         the lacto-N-biosyl group is linked to         -   the galactose of the lacto-N-biosyl group with a 2-3             interglycosidic linkage and/or         -   the N-acetyl-glucosamine of the lacto-N-biosyl group with a             2-6 interglycosidic linkage and/or         -   the galactose of the N-acetyl-lactosaminyl group with a 2-6             interglycosidic linkage.

According to a further preferred aspect, compounds as obtained according to the method of diversification of the present invention, preferably compounds according to general subformulae 3a, 3b or 4 may be selected from the group of: 2′-fucosyllactose, 3-fucosyllactose, 2′,3-difucosyllactose, 3′-sialyllactose, 6′-sialyllactose, 3′-sialyl-3-fucosyllactose, lacto-N-tetraose, lacto-N-neotetraose, LNFP-I, LNFP-II, LNFP-III, LNFP-V, LST-a, LST-b, LST-c, FLST-a, FLST-b, FLST-c, LNDFH-I, LNDFH-II, LNDFH-III, DS-LNT, FDS-LNT I and FDS-LNT II, or salts thereof. The core structures of these compounds are shown in Table 6 above.

The compounds obtained by the method of the present invention, after incubation step c) and optionally a repetition of steps according to step d) or e), are obtained depending on the selection of the at least one enzyme comprising a transglycosidase activity as described above. Such an enzyme may be selected depending on the desired linkage or modification to be carried out during diversification using the method of the present invention.

Wild type or engineered fucosidases as defined above may be utilized herein, displaying transfucosidase activity and show a α,1-2, α,1-3 and/or α,1-4 regioselectivity are targeted in the present invention. Such wild type or engineered fucosidases preferably display transfucosidase activity and catalyze the transfer of the fucosyl residue to:

-   -   the galactose of the lacto-N-biosyl group with α,1-2         interglycosidic linkage and/or     -   the N-acetyl-glucosamine of the lacto-N-biosyl group with α,1-4         interglycosidic linkage and/or     -   the N-acetyl-glucosamine of the N-acetyl-lactosaminyl group with         α,1-3 interglycosidic linkage;

Such linkages are highly preferred in the context of the method of the present invention and the compounds claimed herein, when using wild type or engineered fucosidases.

Additionally, wild type or engineered sialidases as defined above may be utilized herein, which display trans-sialidase activity and show a α,2-3 and/or α,2-6 regioselectivity. Such linkages are preferably targeted in the present invention. Such wild type or engineered sialidases preferably display trans-sialidase activity and catalyze the transfer of the sialyl residue to:

-   -   the galactose of the lacto-N-biosyl group with 2-3         interglycosidic linkage and/or     -   the N-acetyl-glucosamine of the lacto-N-biosyl group with 2-6         interglycosidic linkage and/or     -   the galactose of the N-acetyl-lactosaminyl group with 2-6         interglycosidic linkage.

Such linkages are highly preferred in the context of the method of the present invention and the compounds claimed herein, when using wild type or engineered sialidases. Furthermore, wild type or engineered lacto-N-biosidases as defined above may be utilized herein, which display trans-lacto-N-biosidase activity and show a β,1-3 regioselectivity. Such linkages are preferably targeted in the present invention. Such wild type or engineered lacto-N-biosidases preferably display trans-lacto-N-biosidase activity and catalyze the transfer of the lacto-N-biosyl residue to N-acetyl-lactosaminyl group with 1-3 interglycosidic linkage are targeted in the present invention. Such linkages are highly preferred in the context of the method of the present invention and the compounds claimed herein, when using wild type or engineered lacto-N-biosidases.

Finally, wild type or engineered glycosidases as defined above may be utilized herein, which display trans-N-acetyllactosaminidase activity and show a β,1-3 and/or β,1-6 regioselectivity are targeted in the present invention. Such wild type or engineered glycosidases preferably display trans-N-acetyllactosaminidase activity and catalyze the transfer of the N-acetyl-lactosaminyl residue to another N-acetyl-lactosaminyl group with 1-3 or 1-6 interglycosidic linkage. Such linkages are highly preferred in the context of the method of the present invention and the compounds claimed herein, when using wild type or engineered N-acetyllactosaminidases.

According to another specific aspect of the method of the present invention the compounds obtained according to the method of the present invention, preferably compounds according to any of formulae 1, 2, 3 or 4 or of general subformulae 1a, 1b or 2 or of general subformulae 3a, 3b or 4 are optionally subjected to a purification reaction preferably via crystallization or precipitation.

According to a specific aspect of the method of the present invention the compounds obtained according to the method of the present invention, preferably compounds according to any of formulae 1, 2, 3 or 4 or of general subformulae 1a, 1b or 2 or of general subformulae 3a, 3b or 4 are optionally spray-dried.

According to a very particular aspect, the compounds obtained according to the method of the present invention may be one or more naturally occurring HMO R-glycosides, preferably compounds according to formulae 1 or 2 or of general subformulae 1a, 1b or 2, or one or more naturally occurring HMOs, preferably compounds according to formulae 3 or 4 or of general subformulae 3a, 3b or 4. Naturally occurring HMOs are listed in TADASU URASHIMA et al, MILK OLIGOSACCHARIDES, Nova Biomedical Books, New York, 2011, ISBN: 978-1-61122-831-1, Table 4 in pp. 14-25.

Furthermore, according to a very particular aspect, the compounds obtained according to the method of the present invention may be one or more HMOs, wherein the HMO is derivatized with benzyl.

According to a further specific aspect of the method of the present invention the compounds obtained according to the method of the present invention, preferably single compounds or a mixture of two or more compounds according to any of formulae 1 or 2 or of general subformulae 1a, 1b or 2 are subjected to a hydrogenolysis reaction subsequent to incubation according to step c) and/or a further repetition according to step d) or e), resulting in the formation of single HMOs or a mixture of two or more HMOs characterized by general formulae 3 and 4.

In the hydrogenolysis step, a single compound or a mixture of two or more compounds according to any of formulae 1 or 2 or of general subformulae 1a, 1b or 2 after incubation step c), d) or e), is subjected to a hydrogenolysis reaction, e.g. as defined herein. In this context, such a hydrogenolysis step is preferably carried out to obtain the naturally occurring naked HMOs, e.g. as defined according to any of the formulae as defined above, and preferably to remove possible protecting groups, such as benzyl groups.

Catalytic hydrogenolysis typically takes place in a protic solvent or in a mixture of protic solvents. A protic solvent may be selected from the group consisting of water, acetic acid or C₁-C₆ alcohols. A mixture of one or more protic solvents with one or more suitable aprotic organic solvents partially or fully miscible with the protic solvent(s) (such as THF, dioxane, ethyl acetate or acetone) may also be used. Water, one or more C₁-C₆ alcohols or a mixture of water and one or more C₁-C₆ alcohols are preferably used as the solvent system. Solutions containing the carbohydrate derivatives in any concentration or suspensions of the carbohydrate derivatives in the solvent(s) used are also applicable. The reaction mixture is stirred at a temperature in the range of 10-100° C., preferably between 20-50° C., in a hydrogen atmosphere of 1-50 bar absolute (100 to 5000 kPa) in the presence of a catalyst such as palladium, Raney nickel or any other appropriate metal catalyst, preferably palladium on charcoal or palladium black, until reaching the completion of the reaction. Transfer hydrogenolysis may also be performed, when the hydrogen is generated in situ from cyclohexene, cyclohexadiene, formic acid or ammonium formate. Addition of organic or inorganic bases or acids and/or basic and/or acidic ion exchange resins can also be used to improve the kinetics of the hydrogenolysis. The use of basic substances is especially preferred when halogen substituents are present on the substituted benzyl moieties of the precursors and/or the formation of mannosamine base is desirable. Preferred organic bases include, but are not limited to, triethylamine, diisopropyl ethylamine, ammonia, ammonium carbamate and diethylamine. An organic or an inorganic acid is favourably used as a co-solvent or additive in cases when mannosamine salts are the intended products. Preferred acids include, but are not limited to, formic acid, acetic acid, propionic acid, chloroacetic acid, dichloroacetic acid, trifluoroacetic acid, HCl and HBr. The conditions proposed above allow simple, convenient and delicate removal of the solvent(s) giving rise to a mixture or blend of pure HMOs.

Accordingly, a further aspect of the present invention relates to providing single compounds or mixture of two or more compounds, which compounds are characterized by

-   -   general formula 1 and salts thereof:

-   -   wherein     -   R is a group removable by hydrogenolysis,     -   R₁ is fucosyl or H,     -   R₂ is selected from N-acetyl-lactosaminyl and lacto-N-biosyl         groups, wherein the N-acetyl lactosaminyl group may carry a         glycosyl residue comprising one or more N-acetyl-lactosaminyl         and/or one or more lacto-N-biosyl groups; any         N-acetyl-lactosaminyl and lacto-N-biosyl group can be         substituted with one or more sialyl and/or fucosyl residue,     -   R₃ is H or an N-acetyl-lactosaminyl group optionally substituted         with a glycosyl residue comprising one or more         N-acetyl-lactosaminyl and/or one or more lacto-N-biosyl groups;         any N-acetyl-lactosaminyl and lacto-N-biosyl group can be         substituted with one or more sialyl and/or fucosyl residue,     -   with the proviso that, if provided alone, the compound is not         LNnT R-glycoside or LNT benzyl glycoside;     -   or general formula 2 and salts thereof

-   -   wherein     -   R is a group removable by hydrogenolysis,     -   R₁ independently of each other is fucosyl or H     -   R₄ independently of each other is sialyl or H,     -   with the proviso that, that at least one of R₁ or R₄ is not H,         and, if provided alone, the compound is not 3′-sialyllactose         benzyl glycoside sodium salt or 6′-sialyllactose R-glycoside.

Even more preferably, the invention relates to either single human milk oligosaccharide derivatives, or a diversified mixture comprising two or more human milk oligosaccharides (HMOs) derivatives, wherein compounds of formulae 1 and 2 defined above are further characterized by general formulae 1a, 1b or 2 and salts thereof

wherein

R, R₁ and R₄ are as defined above,

R_(2a) is an N-acetyl-lactosaminyl group optionally substituted with a glycosyl residue comprising one N-acetyl-lactosaminyl and/or one lacto-N-biosyl group; any N-acetyl-lactosaminyl and lacto-N-biosyl group can be substituted with one or more sialyl and/or fucosyl residue,

R_(3a) is H or an N-acetyl-lactosaminyl group optionally substituted with a lacto-N-biosyl group; any N-acetyl-lactosaminyl and lacto-N-biosyl group can be substituted with one or more sialyl and/or fucosyl residue,

R_(2b) is a lacto-N-biosyl group optionally substituted with sialyl and/or fucosyl residue, and

R_(3b) is H or an N-acetyl-lactosaminyl group optionally substituted with one or two N-acetyl-lactosaminyl and/or one lacto-N-biosyl group; any N-acetyl-lactosaminyl and lacto-N-biosyl group can be substituted with one or more sialyl and/or fucosyl residue.

Particularly preferably, compounds defined above are characterized by their linkages and modifications. Preferably, the compounds defined according to general formulae 1a and 1b, are characterized in that:

-   -   the N-acetyl-lactosaminyl group in the glycosyl residue of         R_(2a) in general formula 1a is attached to the another         N-acetyl-lactosaminyl group with a 1-3 interglycosidic linkage,     -   the lacto-N-biosyl group in the glycosyl residue of R_(2a) in         general formula 1a is attached to the N-acetyl-lactosaminyl         group with a 1-3 interglycosidic linkage,     -   the lacto-N-biosyl group in the glycosyl residue of R_(3a) in         general formula 1a is attached to the N-acetyl-lactosaminyl         group with a 1-3 interglycosidic linkage,     -   the N-acetyl-lactosaminyl group in the glycosyl residue of         R_(3b) in general formula 1b is attached to another         N-acetyl-lactosaminyl group with a 1-3 or 1-6 interglycosidic         linkage,     -   the lacto-N-biosyl group in the glycosyl residue of R_(3b) in         general formula 1b is attached to the N-acetyl-lactosaminyl         group with a 1-3 interglycosidic linkage.

Preferably, the compounds characterized by general formula 1a represent the R-glycosides of lacto-N-tetraose, para-lacto-N-hexaose, para-lacto-N-neohexaose, lacto-N-neohexaose, para-lacto-N-octaose and lacto-N-neooctaose optionally substituted with one or more sialyl and/or fucosyl residue, and general formula 1b represents the R-glycosides of lacto-N-tetraose, lacto-N-hexaose, lacto-N-octaose, iso-lacto-N-octaose, lacto-N-decaose and lacto-N-neodecaose optionally substituted with one or more sialyl and/or fucosyl residue.

Preferably, the compounds characterized by general formula 1a and 1b substituted with one or more sialyl and/or fucosyl residue are further characterized in that:

-   -   the fucosyl residue attached to the N-acetyl-lactosaminyl and/or         the lacto-N-biosyl group is linked to         -   the galactose of the lacto-N-biosyl group with a 1-2             interglycosidic linkage and/or         -   the N-acetyl-glucosamine of the lacto-N-biosyl group with a             1-4 interglycosidic linkage and/or         -   the N-acetyl-glucosamine of the N-acetyl-lactosaminyl group             with a 1-3 interglycosidic linkage,     -   the sialyl residue attached to the N-acetyl-lactosaminyl and/or         the lacto-N-biosyl group is linked to         -   the galactose of the lacto-N-biosyl group with a 2-3             interglycosidic linkage and/or         -   the N-acetyl-glucosamine of the lacto-N-biosyl group with a             2-6 interglycosidic linkage and/or         -   the galactose of the N-acetyl-lactosaminyl group with a 2-6             interglycosidic linkage.

According to a further preferred aspect, compounds as defined above may be selected from the group of: R-glycosides of 2′-fucosyllactose, 3-fucosyllactose, 2′,3-difucosyllactose, 3′-sialyllactose, 6′-sialyllactose, 3′-sialyl-3-fucosyllactose, lacto-N-tetraose, lacto-N-neotetraose, LNFP-I, LNFP-II, LNFP-III, LNFP-V, LST-a, LST-b, LST-c, FLST-a, FLST-b, FLST-c, LNDFH-I, LNDFH-II, LNDFH-III, DS-LNT, FDS-LNT I and FDS-LNT II, or salts thereof. The R-glycosides may be alpha or beta-anomers. Preferably, said R-glycosides are the beta-anomers and more preferably R is benzyl.

According to a further embodiment, the method of the present invention further comprises addition of the compounds obtained in the incubation step and/or after the hydrogenolysis step to a consumable product, preferably as defined herein. The consumable product is preferably at least one of a pharmaceutical or nutritional formulation and preferably a liquid or a solid. According to another embodiment, the method may further comprise the addition of pharmaceutically acceptable carriers and/or the addition of prebiotics to the compounds obtained in the incubation step and/or after the hydrogenolysis step.

According to a second aspect, the present invention also provides a compound, particularly a diversified mixture of HMOs, characterized as specified above, obtained or obtainable by the method of the present invention as described herein. According to a further embodiment of the second aspect, the present invention provides a compound, preferably a mixture of compounds, more preferably a mixture of HMOs, obtained or obtainable by the method of the present invention as described herein. In this context, such a mixture of compounds obtained or obtainable by the method as described herein is preferably to be understood as a mixture of at least 2 to 10, 2 to 10, 2 to 20, 2 to 20, 2 to 100, 2 to 200, or even more different compounds as generally defined above. Such compounds may be preferably selected without restriction from any of the compounds as defined according to any of formulae 1, 2, 3 or 4 or of any subformulae or selection as defined above.

According to a third aspect, the present invention also provides compounds, which may be utilized in the present invention, e.g. as a donor or acceptor, and compounds, which may be obtained during the method of diversification of the present invention.

The present invention also provides or utilizes salts of herein defined compounds. Such salts may be preferably selected from salts of the compounds according to general formulae 1-4 or subformulae thereof, which contain at least one sialyl residue, in salt form: an associated ion pair consisting of the negatively charged acid residue of sialylated oligosaccharides falling under general formulae 1-4 or subformulae thereof and one or more cations in any stoichiometric proportion. Cations, as used in the present context, are atoms or molecules with positive charge. The cation may be inorganic or organic. Preferred inorganic cations are ammonium ion, alkali metal, alkali earth metal and transition metal ions, more preferably Na⁺, K⁺, Ca²⁺, Mg²⁺, Ba²⁺, Fe²⁺, Zn²⁺, Mn²⁺ and Cu²⁺, most preferably K⁺, Ca²⁺, Mg²⁺, Ba²⁺, Fe²⁺ and Zn²⁺. Basic organic compounds in positively charged form may be relevant organic cations. Such preferred positively charged counterparts are diethyl amine, triethyl amine, diisopropyl ethyl amine, ethanolamine, diethanolamine, triethanolamine, imidazole, piperidine, piperazine, morpholine, benzyl amine, ethylene diamine, meglumin, pyrrolidine, choline, tris-(hydroxymethyl)-methyl amine, N-(2-hydroxyethyl)-pyrrolidine, N-(2-hydroxyethyl)-piperidine, N-(2-hydroxyethyl)-piperazine, N-(2-hydroxyethyl)-morpholine, L-arginine, L-lysine, oligopeptides having L-arginine or L-lysine unit or oligopeptides having a free amino group on the N-terminal, etc., all in protonated form. Such salt formations can be used to modify characteristics of the complex molecule as a whole, such as stability, compatibility to excipients, solubility and ability to form crystals.

According to a particular embodiment of the third aspect, the compounds as defined herein may be subjected to a hydrogenolysis, preferably, if R is not H, even more preferably, if R is benzyl. Such a hydrogenolysis is preferably carried out as described above. Groups R are preferably as defined herein to be cleavable in a hydrogenolysis reaction.

In a further embodiment of the third aspect, compounds or a mixture of compounds, more preferably a mixture of HMOs, obtained or obtainable by the method of the present invention as described herein or any further compound as defined herein, may be used for the preparation of a consumer product, preferably for the preparation of a pharmaceutical composition, a nutritional formulation or a food supplement. Such compounds or a mixture of compounds, more preferably a mixture of HMOs, obtained or obtainable by the method of the present invention as described herein is particularly effective in the improvement and maturation of the immune system of neonatal infants, and has preventive effect against secondary infections following viral infections such as influenza. The use of compounds or a mixture of compounds, more preferably a mixture of HMOs, obtained or obtainable by the method of the present invention as described herein as a prebiotic enhances the beneficial effects and efficiency of probiotics, such as Lactobacillus and Bifidobacterium species, in promoting the development of an early bifidogenic intestinal microbiota in infants, in reducing the risk of development or allergy and/or asthma in infants, in preventing and treating pathogenic infections in such as diarrhoea in infants.

In a fourth aspect, the present invention provides a pharmaceutical composition comprising compounds or a mixture of compounds, more preferably a mixture of HMOs, obtained or obtainable by the method of the present invention as described herein, and preferably further comprising a pharmaceutically acceptable carrier. “Pharmaceutically acceptable carriers” include but not limited to additives, adjuvants, excipients and diluents (water, gelatine, talc, sugars, starch, gum arabic, vegetable gums, vegetable oils, polyalkylene glycols, flavouring agents, preservatives, stabilizers, emulsifying agents, lubricants, colorants, fillers, wetting agents, etc.). Suitable carriers are described in the most recent edition of Remington's Pharmaceutical Sciences, a standard reference text in the field. The dosage form for administration includes, for example, tablets, powders, granules, pills, suspensions, emulsions, infusions, capsules, injections, liquids, elixirs, extracts and tinctures.

In a fifth aspect, nutritional formulations are provided such as foods or drinks, preferably comprising compounds or a mixture of compounds, more preferably a mixture of HMOs, obtained or obtainable by the method of the present invention as described herein. The nutritional formulation may contain edible micronutrients, vitamins and minerals as well. The amounts of such ingredient may vary depending on whether the formulation is intended for use with normal, healthy infants, children, adults or subjects having specialized needs (e.g. suffering from metabolic disorders). Micronutrients include for example edible oils, fats or fatty acids (such as coconut oil, soy-bean oil, monoglycerides, diglycerides, palm olein, sunflower oil, fish oil, linoleic acid, linolenic acid etc.), carbohydrates (such as glucose, fructose, sucrose, maltodextrin, starch, hydrolized cornstarch, etc.) and proteins from casein, soy-bean, whey or skim milk, or hydrolysates of these proteins, but protein from other source (either intact or hydrolysed) may be used as well. Vitamins may be chosen from the group consisting of vitamin A, B1, B2, B5, B6, B12, C, D, E, H, K, folic acid, inositol and nicotinic acid. The nutritional formula may contain the following minerals and trace elements: Ca, P, K, Na, Cl, Mg, Mn, Fe, Cu, Zn, Se, Cr or I.

According to a general embodiment of the fifth aspect, a nutritional formulation as defined above may further contain one or more probiotics, e.g. facto bacteriae, Bifidobacterium species, prebiotics such as fructooligosaccharides and galactooligosaccharides, proteins from casein, soy-bean, whey or skim milk, carbohydrates such as lactose, saccharose, maltodextrin, starch or mixtures thereof, lipids (e.g. palm olein, sunflower oil, safflower oil) and vitamins and minerals essential in a daily diet. Probiotics are preferably also contained in the nutritional formulation in an amount sufficient to achieve the desired effect in an individual, preferably in infants, children and/or adults.

In a preferred embodiment, the nutritional formulation as defined above is an infant formula. In the context of the present invention, the term “infant formula” preferably means a foodstuff intended for particular nutritional use by infants during the first 4-6 months or even 4 to 12 months of life and satisfying by itself the nutritional requirements of infants. It may contain one or more probiotic Bifidobacterium species, prebiotics such as fructooligosaccharides and galactooligosaccharides, proteins from casein, soy-bean, whey or skim milk, carbohydrates such as lactose, saccharose, maltodextrin, starch or mixtures thereof, lipids (e.g. palm olein, sunflower oil, safflower oil) and vitamins and minerals essential in a daily diet.

In the sixth aspect, a food supplement may be provided. Such a food supplement preferably contains ingredients as defined for nutritional food above, e.g. compounds or a mixture of compounds, more preferably a mixture of HMOs, obtained or obtainable by the method of the present invention as described herein, vitamins, minerals, trace elements and other micronutritients, etc. The food supplement may be for example in the form of tablets, capsules, pastilles or a liquid. The supplement may contain conventional additives selected from but not limited to binders, coatings, emulsifiers, solubilising agents, encapsulating agents, film forming agents, adsorbents, carriers, fillers, dispersing agents, wetting agents, gellifying agents, gel forming agents, etc.

According to a preferred embodiment, the food supplement is a digestive health functional food, as the administration of compounds or a mixture of compounds, more preferably a mixture of HMOs, obtained or obtainable by the method of the present invention as described herein, provides a beneficial effect on digestive health. A digestive health functional food is preferably a processed food used with the intention to enhance and preserve digestive health by utilizing compounds or a mixture of compounds, more preferably a mixture of HMOs, obtained or obtainable by the method of the present invention as described herein, as physiologically functional ingredients or components in the form of tablets, capsules, powders, etc. Different terms such as dietary supplement, nutraceutical, designed food, or health product may also be used to refer to a digestive health functional food.

In a further aspect, compounds or a mixture of compounds, more preferably a mixture of HMOs, obtained or obtainable by the method of the present invention as described herein, may be used for the preparation of nutritional formulations including foods, drinks and feeds, preferably infant formulas, food supplements and digestive health functional foods, preferably any of these as described above. The nutritional formulation may be prepared in any usual manner.

To assist in the understanding of the present invention, explanation of the outcome of the methods of the invention when applied to certain combinations of compounds and enzymes is described below.

Suitably, the compound provided in step a) of the method may be 2′-fucosyllactose, and the enzyme provided in step b) may be a transfucosidase. As 2′-fucosyllactose may act as donor and acceptor in this system, the outcome of the incubation step c) may be the production of difucosyllactose and lactose. As lactose is not specifically a human milk oligosaccharide, it is considered that the outcome of step c) is the production of a single HMO, and thus according to the more preferred embodiment of the invention, a second iteration of at least step a) and step c) or step b) and step c) must be performed to arrive at a mixture of HMOs.

Suitably, the compounds provided in step a) of the method may be 3′-sialyllactose (donor) and 3-fucosyllactose (acceptor), and the enzyme provided in step b) may be a transsialidase. The outcome of the incubation step c) may be the production of sialyl-fucosyl-lactose and lactose. As lactose is not specifically a human milk oligosaccharide, it is considered that the outcome of step c) is the production of a single HMO, and thus according to the more preferred embodiment of the invention, a second iteration of at least step a) and step c) or step b) and step c) must be performed to arrive at a mixture of HMOs.

Suitably, the compounds provided in step a) of the method may be 3′-sialyllactose (donor) and lactose (acceptor), and the enzyme provided in step b) may be a 1-6-selective transsialidase. The outcome of the incubation step c) may be the production of 6-sialyl-lactose and lactose. As lactose is not specifically a human milk oligosaccharide, it is considered that the outcome of step c) is the production of a single HMO, and thus according to the more preferred embodiment of the invention, a second iteration of at least step a) and step c) or step b) and step c) must be performed to arrive at a mixture of HMOs.

Suitably, the compounds provided in step a) of the method may be 2′-fucosyllactose (donor) and lactose (acceptor), and the enzyme provided in step b) may be a 1-3-selective transfucosidase. The outcome of the incubation step c) may be the production of 3-fucosyllactose and lactose. As lactose is not specifically a human milk oligosaccharide, it is considered that the outcome of step c) is the production of a single HMO, and thus according to the more preferred embodiment of the invention, a second iteration of at least step a) and step c) or step b) and step c) must be performed to arrive at a mixture of HMOs.

Suitably, the compounds provided in step a) of the method may be 3′-sialyllactose (donor) and LNT (acceptor), and the enzyme provided in step b) may be a transsialidase. The outcome of the incubation step c) may be the production of sialyl-LNT and lactose. As lactose is not specifically a human milk oligosaccharide, it is considered that the outcome of step c) is the production of a single HMO, and thus according to the more preferred embodiment of the invention, a second iteration of at least step a) and step c) or step b) and step c) must be performed to arrive at a mixture of HMOs.

Suitably, the compounds provided in step a) of the method may be LNnT (donor and acceptor), and the enzyme provided in step b) may be a trans-N-acetyl-lactosaminidase. The outcome of the incubation step c) may be the production of para-lacto-N-neohexaose (pLNnH) or lacto-N-neohexaose (LNnH) and lactose. As lactose is not specifically a human milk oligosaccharide, it is considered that the outcome of step c) is the production of a single HMO, and thus according to the more preferred embodiment of the invention, a second iteration of at least step a) and step c) or step b) and step c) must be performed to arrive at a mixture of HMOs.

Suitably, the compounds provided in step a) of the method may be LNnT (donor) and LNT (acceptor), and the enzyme provided in step b) may be a trans-N-acetyl-lactosaminidase. The outcome of the incubation step c) may be the production of lacto-N-hexaose (LNH) and lactose. As lactose is not specifically a human milk oligosaccharide, it is considered that the outcome of step c) is the production of a single HMO, and thus according to the more preferred embodiment of the invention, a second iteration of at least step a) and step c) or step b) and step c) must be performed to arrive at a mixture of HMOs.

Suitably, the compounds provided in step a) of the method may be LNT (donor) and LNnT (acceptor), and the enzyme provided in step b) may be a trans-lacto-N-biosidase. The outcome of the incubation step c) may be the production of para-lacto-N-hexaose (pLNH) and lactose. As lactose is not specifically a human milk oligosaccharide, it is considered that the outcome of step c) is the production of a single HMO, and thus according to the more preferred embodiment of the invention, a second iteration of at least step a) and step c) or step b) and step c) must be performed to arrive at a mixture of HMOs.

Similar variations using the corresponding benzyl glycosides of the donors and/or acceptors can be used.

In the present invention, if not otherwise indicated, different features of alternatives and embodiments may be combined with each other, where suitable.

Whilst the invention has been described with reference to a preferred embodiment, it will be appreciated that various modifications are possible within the scope of the invention.

In this specification, unless expressly otherwise indicated, the word ‘or’ is used in the sense of an operator that returns a true value when either or both of the stated conditions is met, as opposed to the operator ‘exclusive or’ which requires that only one of the conditions is met. The word ‘comprising’ is used in the sense of ‘including’ rather than in to mean ‘consisting of’. All prior teachings acknowledged above are hereby incorporated by reference. No acknowledgement of any prior published document herein should be taken to be an admission or representation that the teaching thereof was common general knowledge in Australia or elsewhere at the date hereof.

EXPERIMENTAL Example 1 General Procedure for Transglycosylation Reactions

A solution of appropriate glycosyl donor(s) and glycosyl acceptor(s) (10 mM-1M) such as compounds according to general formula 2 and 4, LNT, LNT-OR, LNnT or LNnT-OR were incubated in incubation buffer at a pH range from 5.0 to 9.0 with recombinant glycosidase, transglycosidase or glycosynthase, such as α-fucosidase, α-transfucosidase, α-fucosynthase, α-sialidase, α-transsialidase, β-lacto-N-biosidase, β-trans-lacto-N-biosidase, β-N-acetyllactosaminidase or β-trans-N-acetyllactosaminidase. The reaction mixture was stirred at a temperature range from 15 to 70° C. Samples were taken at different times of the reaction, the reaction was stopped by the addition of 1M NaHCO₃-solution at pH=10 and the products were analyzed by HPLC, or/and LC-MS, or/and LC/MS-MS. After completion, the enzyme was denatured and centrifuged. The resulting solution was evaporated under reduced pressure. After lyophilisation, the dry residue was dissolved in water and products were purified by biogel chromatography (P-2 Biogel, 16×900 mm) with water or by reverse phase chromatography.

The following recombinant enzymes used and tested in transglycosylation reaction:

Transfucosidase P25 from Thermotoga maritima (see seq. ID 1) containing mutations G226S Y237H T264A L322P Transfucosidase M3 from Thermotoga maritima (see seq. ID 1) containing mutations Y237H Y267F L322P. Transfucosidase C2 from Thermotoga maritima (see seq. ID 1) containing mutations T264A Y267F L322P. Transsialidase from Trypanosoma cruzi (see seq. ID 15, 16) Fucosidase Blon_(—)2336 from Bifidobacterium longum subsp. infantis ATCC 15697 (see seq. ID 5)

These transglycosidases were produced in E. coli as reported in Osanjo et al. Biochemistry 46, 1022 (2007), Seta et al. Appl. Environ. Microbiol. 78, 795 (2012), Agustí et al. Glycobiology 14, 659 (2004) and Neubacher et al. Org. Biomol. Chem. 3, 1551 (2005). Purified transglycosidases were stored at −20° C. to +4° C.

Example 2 Sialylation Using 3-SL as Donor

General procedure: a solution of 3-SL and the appropriate sialyl acceptor in incubation buffer (0.5 ml, 100 mM Tris/HCl, pH 7.0) was incubated with recombinant transsialidase from T. cruzi (45 μl, 90 μg/ml) at 15° C. Samples were taken after 3, 6 and 24 hours (50 μl each) and the progression of the reaction was monitored on TLC.

Medium to high conversion was detected in the following sialylation reactions:

donor: 3-SL (75 mM), acceptor: LNT (50 mM), product: sialylated LNT donor: 3-SL (75 mM), acceptor: LNnT (50 mM), product: sialylated LNnT donor: 3-SL (75 mM), acceptor: 3-FL (25 mM), product: sialylated 3-FL

Example 3 Fucosylation with 2′-FL as Donor

General procedure: a solution of 2′-FL and LNT in degassed incubation buffer (0.5 ml, 50 mM citrate-phosphate, 145 mM NaCl, pH 5.5) was incubated with transfucosidase (P25 from Thermotoga Maritima, M3 from Thermotoga Maritima) at 60° C. Sample was taken after 21 hours and the conversion was determined by HPLC. Results:

P25 mutant:

-   -   500 mM 2′-FL, 500 mM LNT, conversion: 25% fucosylated LNT         (position of fucosylation not determined);         1000 mM 2′-FL, 500 mM LNT, conversion: 31% fucosylated LNT         (position of fucosylation not determined)+4% difucosylated LNT         (position of fucosylations not determined);         M3 mutant:     -   500 mM 2′-FL, 500 mM LNT, conversion: 36% fucosylated LNT         (position of fucosylation not determined).

Example 4 Fucosylation with 2′-FL as Donor

General procedure: A solution of 2′-FL and acceptor (10-500 mM, donor acceptor ratio is 5:1 to 1:5) was incubated in degassed incubation buffer (1 ml, 50 mM sodium citrate/phosphate buffer and 150 mM NaCl) at pH=5.5 with transfucosidase (P25 from Thermotoga Maritima, M3 from Thermotoga Maritima) at 60° C. for 24 hours. Samples were taken at different times of the reaction, the reaction was stopped by the addition of 1M NaHCO₃-solution at pH=10 and analyzed by TLC and/or HPLC. After completion, the enzyme was denatured and centrifuged. The resulting solution was evaporated under reduced pressure. After lyophilisation, the dry residue was dissolved in water and purified by biogel chromatography (P-2 Biogel, 16×900 mm) with water or by reverse phase chromatography. The product were identified using LC-MS.

LC-MS conditions: Instrument: AB Sciex API 2000 tandem MS Ionization mode: electrospray in positive mode Scan type: Q1MS Sample insertion mode: HPLC

Column: Phenomenex HILIC 250×4.6 mm

Flow: isocratic (water-acetonitrile 22:78) Flow rate: 1 ml/min Injected volume: 5 μl

Results:

acceptor: Galβ1-3GlcNAcβ1-3Galβ1-4Glcβ1-O-Bn, product: mono fucosylated Galβ1-3GlcNAcβ1-3Galβ1-4Glcβ1-O-Bn, correct molecular mass was confirmed by LC-MS (944 [M+H]⁺, 961 [M+NH₄]⁺, 966 [M+Na]⁺), acceptor: Galβ1-4GlcNAcβ1-3Galβ1-4Glcβ1-O-Bn, product: mono fucosylated Galβ1-4GlcNAcβ1-3Galβ1-4Glcβ1-O-Bn, correct molecular mass was confirmed by LC-MS (944 [M+H]⁺, 961 [M+NHa]⁺, 966 [M+Na]⁺).

Example 5 Fucosylation with 3-FL as Donor

General procedure: A solution of 3-FL as donor (200 mM) with 2′-FL as acceptor (200 mM) was incubated in incubation buffer KHPO₄ (100 mM) at pH 7.0 with the recombinant fucosidase Blon_(—)2336 from Bifidobacterium longum subsp. infantis ATCC 15697. The reaction mixture was stirred at 30° C. for 30 min. The reaction was stopped by addition of 1M NaHCO₃-solution at pH=10. Products were analyzed by HPLC.

Product detected: 2′,3-difucosyllactose (identified by HPLC compared to the reference standard sample of 2′,3-difucosyllactose)

Example 6 Sialylation of Multiple Acceptors Using 3-SL as Donor

Protocol: A solution of 3-SL as donor (75 mM) with 3-FL, lacto-N-tetraose and lacto-N-neotetraose as acceptors (25 mM each) was incubated in incubation buffer Tris-HCl (100 mM) at pH 7.0 with recombinant transsialidase from Trypanosoma cruzi. The reaction mixture was stirred at a temperature of 30° C. for 24 h. The reaction was stopped by addition of 1M NaHCO₃-solution at pH=10. Products were analyzed by HPLC and LC-MS using reference standards (for SFL, LSTa, LSTd).

Products detected: 3′-sialyl-3-fucosyllactose, LSTa: Neu5Acα2-3Galβ1-3GlcNAcβ1-3Galβ1-4Glc, sialylated lacto-N-neotetraose (LSTd): Neu5Acα2-3Galβ1-4GlcNAcβ1-3Galβ1-4Glc, disialylated lacto-N-tetraose and/or disialylated lacto-N-neotetraose, correct molecular mass was confirmed by LC-MS (1290 [M+H]⁺, 1307 [M+NH₄]⁺, 1328 [M+K]⁺).

Example 7 Fucosylation of Multiple Acceptors Using 3-FL as Donor

Protocol: A solution of 3-fucosyllactose as donor (200 mM) with lacto-N-tetraose-β-OBn and lacto-N-neotetraose-β-OBn as acceptors (100 mM each) was incubated in incubation buffer KHPO₄ (100 mM) at pH 7.0 with the recombinant fucosidase Blon_(—)2336 from Bifidobacterium longum subsp. infantis ATCC 15697. The reaction mixture was stirred at 30° C. for 30 min. Products were analyzed by HPLC and LC-MS.

Products detected: fucosylated lacto-N-tetraose-(β)-OBn, fucosylated lacto-N-neotetraose-(β)-OBn (β).

Example 8 Glycosylation of LNT Using Multiple Donors and Enzymes

Protocol: In a first cycle, a solution of 3′-sialyllactose as donor (100 mM) with lacto-N-tetraose as acceptor (200 mM) was incubated in incubation buffer KHPO₄ (100 mM) at pH 7.0 with the recombinant transsialidase from Trypanosoma cruzi. The reaction mixture was stirred at a temperature of 30° C. for 24 hours.

In a second cycle, the resulting reaction mixture was incubated for additional 24 hours at 30° C. after adding 200 mM of 2′-fucosyllactose and the recombinant transfucosidase M3 from Thermotoga maritima.

In a third cycle, the resulting reaction mixture was incubated for additional 30 minutes at 30° C. after adding 100 mM of 3-fucosyllactose and the recombinant fucosidase Blon_(—)2336 from Bifidobacterium longum subsp. infantis ATCC 15697. The reaction was stopped by addition of 1M NaHCO₃-solution at pH=10 and products were analyzed by HPLC, LC-MS and LC-MS-MS.

LC-MS conditions: Instrument: AB Sciex API 2000 tandem MS Ionization mode: electrospray in positive mode Scan type: Q1MS Sample insertion mode: HPLC Column: TSK Gel amide 80 (Tosoh, 3 μM, 150×4.6 mm) Eluent: 10 mM ammonium formate buffer pH=6-acetonitrile: 30%/70% Flow rate: 1 ml/min Injected volume: 5 μl

Results:

Retention Molecular mass Mass (Dalton) of the main fragment time (min) (Dalton) ions of the MH⁺ in MS/MS 6.6 633 12.3 998 (sialyl-LNT) 981, 819, 657, 546, 454, 366, 274, 204, 186, 168 16.5 707 19.9 853 (fucosyl LNT I) 512, 366, 204, 186, 138 25.7 853 (fucosyl LNT II) 512, 366, 350, 204, 186, 138

Example 9 Glycosylation of LNnT Using Multiple Donors and Enzymes

Protocol: In a first cycle, a solution of 3′-sialyllactose as donor (100 mM) and lacto-N-neotetraose as acceptor (200 mM) was incubated in incubation buffer KHPO₄ (100 mM) at pH 7.0 with the recombinant transsialidase from Trypanosoma cruzi. The reaction mixture was stirred at a temperature of 30° C. for 24 hours.

In a second cycle, the resulting reaction mixture was incubated for an additional 24 hours after adding 200 mM of 2′-fucosyllactose and the recombinant transfucosidase M3 from Thermotoga maritima.

In a third cycle, the resulting reaction mixture was incubated for an additional 30 minutes after adding 100 mM of 3-fucosyllactose and the recombinant fucosidase Blon_(—)2336 from Bifidobacterium longum subsp. infantis ATCC 15697. The reaction was stopped by addition of 1M NaHCO₃-solution at pH=10 and products were analyzed by HPLC and LC-MS.

Results (HPLC condition: see Example 8):

Retention Molecular mass Mass (Dalton) of the main fragment time (min) (Dalton) ions of the MH⁺ in MS/MS 6.4 633 7.0 342 11.5 998 (sialyl LNnT) 657, 546, 454, 366, 292, 274, 204, 197, 138 17.0 707 19.8 853 (fucosyl LNnT I) 25.7 853 (fucosyl LNnT II) 512, 366, 204, 186, 138

Example 10 Fucosylation with 3-FL as Donor

General procedure: A solution of 3-FL as donor (200 mM) with LNT as acceptor (200 mM) was incubated in incubation buffer KHPO₄ (100 mM) at pH 7.0 with the recombinant fucosidase Blon_(—)2336 from Bifidobacterium longum subsp. infantis ATCC 15697. The reaction mixture was stirred at 30° C. for 30 min. The reaction was stopped by addition of 1M NaHCO₃-solution at pH=10. Products were analyzed by HPLC.

Product detected: fucosylated LNT (HPLC condition: see Example 8)

Retention Molecular mass Mass (Dalton) of the main fragment time (min) (Dalton) ions of the MH⁺ in MS/MS 25.2 853 512, 366, 350, 204, 186, 138

Example 11 Fucosylation with 3-FL as Donor

General procedure: A solution of 3-FL as donor (200 mM) with LNnT as acceptor (200 mM) was incubated in incubation buffer KHPO₄ (100 mM) at pH 7.0 with the recombinant fucosidase Blon_(—)2336 from Bifidobacterium longum subsp. infantis ATCC 15697. The reaction mixture was stirred at 30° C. for 30 min. The reaction was stopped by addition of 1M NaHCO₃-solution at pH=10. Products were analyzed by HPLC.

Product detected: fucosylated LNnT (HPLC condition: see Example 8)

Retention Molecular mass Mass (Dalton) of the main fragment time (min) (Dalton) ions of the MH⁺ in MS/MS 25.7 853 512, 366, 204, 138

Example 12 Manufacture of benzyl/substituted Benzyl Glycosides A) Benzyl/Substituted Benzyl Lactosides

A1) General procedure: lactose (5 g, 14.6 mmol) and TsOH.H₂O (0.2 g, 1.05 mmol) were added in one portion to a mixture of DMF (20 ml) and benzaldehyde dimethyl acetal (5.5 ml, 35.4 mmol, 2.4 eq.) at room temperature. The reaction mixture was vigorously stirred at 70° C. under exclusion of humidity for 1 hour. After cooling triethyl amine (0.15 ml) was added then the volatile components (MeOH, triethyl amine, remaining benzaldehyde dimethyl acetal) were removed in vacuo. To the reaction mixture the benzyl bromide derivative (1.5 eq.)—predissolved in 5-10 ml of DMF, if the reagent is a solid—was added and the mixture was cooled to 0° C. for 20 min. Still under cooling NaH (0.8 g of a 55% dispersion in mineral oil, 1.3 eq.) was added in one portion, and the mixture was stirred under cooling until the hydrogen formation stopped then at room temperature for 2-3 hours. Methanol (2 ml) was added carefully and the reaction was stirred for a further 5 min. The reaction mixture was portioned between 100 ml of DCM and 100 ml of water and extracted. The water layer was back-extracted twice with 100 ml of DCM. The combined organic phases were evaporated; the residue was dissolved in 100 ml of acetonitrile and extracted with 100 ml of hexane. The acetonitrile was distilled off and the residue was taken up in isopropanol (10 ml) and isopropyl ether (50 ml) at 50° C. The clear solution was cooled to −20° C. for between 2-12 hours. The crystals obtained were filtered off and washed twice with TBME and dried. Recrystallization can be carried out from a mixture of TBME (˜50 ml) and ethanol (˜20 ml).

4-Chlorobenzyl 4′,6′-O-benzylidene-β-lactoside

Yield: 1.71 g

4-Methylbenzyl 4′,6′-O-benzylidene-β-lactoside

Yield: 3.20 g

3-Phenylbenzyl 4′,6′-O-benzylidene-β-lactoside

Yield: 2.70 g

2-Naphthylmethyl 4′,6′-O-benzylidene-β-lactoside

Yield: 1.77 g

B1) To a mixture of one of the above benzylidene acetals (500 mg) in methanol (10 ml) and water (0.5 ml) TFA was added at room temperature and the reaction mixture was stirred for 2-4 hours under exclusion of humidity then evaporated. The remaining material was co-evaporated with ethanol 3-4 times giving a crude solid, which, after drying, can be recrystallized from a mixture of methanol (˜10-35 ml) and water (˜0-2 mL).

4-Chlorobenzyl β-lactoside

Yield: 333 mg

¹³C-NMR (75.1 MHz, D₂O): β=135.25, 133.67, 130.30, 128.70, 103.00, 101.13, 78.39, 75.44, 74.89, 74.49, 72.88, 72.58, 71.03, 70.83, 68.62, 61.11, 60.13.

4-Methylbenzyl β-lactoside

Yield: 439 mg

¹³C-NMR (75.1 MHz, D₂O): δ=138.91, 133.50, 129.37, 129.07, 103.01, 100.96, 78.43, 75.44, 74.87, 74.52, 72.90, 72.59, 71.47, 71.03, 68.63, 61.11, 60.17, 20.34.

3-Phenylbenzyl β-lactoside

Yield: 438 mg

¹³C-NMR (75.1 MHz, d₆-DMSO/d₄-MeOH/D₂O 8:1:1): δ=140.29, 140.24, 138.88, 129.13, 129.02, 127.66, 126.88, 126.83, 126.03, 125.90, 103.95, 102.03, 80.76, 75.65, 75.07, 75.00, 73.34, 73.28, 70.66, 69.81, 68.27, 60.56.

2-Naphthylmethyl β-lactoside

Yield: 378 mg

¹³C-NMR (75.1 MHz, D₂O/d₆-DMSO): δ=134.96, 133.24, 133.12, 128.59, 128.31, 128.08, 127.46, 126.98, 126.90, 126.79, 103.26, 101.59, 78.89, 75.62, 75.09, 74.81, 73.14, 72.81, 71.33, 71.14, 68.75, 61.22, 60.39.

B) Galβ1-3GlcNAcβ1-3Galβ1-4Glcβ1-O-Bn (1-O-benzyl-β-LNT) can be prepared according to A. Malleron et al. Carbohydr. Res. 341, 29 (2006).

C) Galβ1-4GlcNAcβ1-3Galβ1-4Glcβ1-O-Bn (1-O-benzyl-β-LNnT) can be prepared according to WO 2011/100980.

D) Benzyl/substituted benzyl glycoside of sialylated and/or fucosylated lactose, LNT or LNnT can be prepared by anomeric alkylation according to WO 2012/007585. 

1. A method for preparation of one or more human milk oligosaccharides (HMOs) or derivatives or precursors thereof, the method comprising the steps of a) providing at least one compound or a mixture of the compounds selected from the group consisting of: optionally sialylated and/or fucosylated lactose derivatives of general formula 2 and salts thereof:

wherein R is a group removable by hydrogenolysis, R₁ independently of each other is fucosyl or H R₄ independently of each other is sialyl or H, provided that the compound of general formula 2 is not R-glycoside of lactose, if provided alone; optionally sialylated and/or fucosylated lactose derivatives of general formula 4 and salts thereof:

wherein R₁ independently of each other is fucosyl or H R₄ independently of each other is sialyl or H, provided that the compound of general formula 4 is not lactose, if provided alone; lacto-N-tetraose (LNT):

lacto-N-tetraose (LNT) derivatives of the following formula:

wherein R is a group removable by hydrogenolysis; lacto-N-neotetraose (LNnT):

lacto-N-neotetraose (LNnT) derivatives of the following formula:

wherein R is a group removable by hydrogenolysis; b) adding at least one enzyme comprising a transglycosidase activity to the at least one compound or a mixture of compounds provided according to step a); c) incubating the mixture obtained according to step b); d) where both: only two compounds are provided in step a) of which one is 3′-sialyllactose; and the enzyme comprising a transglycosidase activity added in step b) is an enzyme comprising trans-sialidase activity at least steps a) and c) or steps b) and c) are repeated; e) optionally repeating at least steps a) and c) or steps b) and c) with the mixture obtained according to step c) or d); f) optionally subjecting the mixture obtained after step c), d) or e) to a hydrogenolysis reaction.
 2. The method according to claim 1, wherein in step d) where both: only two compounds are provided in step a) of which one is a sialylated lactose derivative of general formula 2 or 4, and the enzyme comprising a transglycosidase activity added in step b) is an enzyme comprising a trans-sialidase activity; at least steps a) and c) or steps b) and c) are repeated.
 3. The method according to claim 1, wherein in step d): only one HMO or derivative or precursor thereof is made as a result of step c), and further where both: only two compounds are provided in step a) of which one is 3′-sialyllactose or a sialylated lactose derivative of general formula 2 or 4, and the enzyme comprising a transglycosidase activity added in step b) is an enzyme comprising a trans-sialidase activity, at least steps a) and c) or steps b) and c) are repeated.
 4. The method according to claim 1, wherein the mixture of compounds comprises at least two, three, four, five, one to five, three to ten, five to ten or even more different compounds as defined according to step a).
 5. The method according to claim 1, wherein the at least one enzyme comprising transglycosidase activity is selected from two, three, four, five, two to five, two to ten, five to ten or even more different enzymes comprising transglycosidase activity.
 6. The method according to claim 1, wherein the compounds or enzymes are added simultaneously or sequentially.
 7. The method according to claim 1, wherein the at least one enzyme comprising transglycosidase activity is an enzyme comprising a trans-fucosidase, trans-sialidase, trans-lacto-N-biosidase and/or trans-N-acetyllactosaminidase activity, preferably an α-trans-fucosidase, α-trans-sialidase, β-trans-Lacto-N-biosidase and/or β-trans-N-acetyllactosaminidase activity.
 8. The method according to claim 1, wherein incubation leads to a mixture of human milk oligosaccharides and/or precursors thereof as defined according to compounds of general formula 1 and salts thereof

wherein R is a group removable by hydrogenolysis, R₁ is fucosyl or H, R₂ is selected from N-acetyl-lactosaminyl and lacto-N-biosyl groups, wherein the N-acetyl lactosaminyl group may carry a glycosyl residue comprising one or more N-acetyl-lactosaminyl and/or one or more lacto-N-biosyl groups; any N-acetyl-lactosaminyl and lacto-N-biosyl group can be substituted with one or more sialyl and/or fucosyl residue, R₃ is H or N-acetyl-lactosaminyl group optionally substituted with a glycosyl residue comprising one or more N-acetyl-lactosaminyl and/or one or more lacto-N-biosyl groups; any N-acetyl-lactosaminyl and lacto-N-biosyl group can be substituted with one or more sialyl and/or fucosyl residue; compounds of general formula 2 and salts thereof

wherein R is a group removable by hydrogenolysis, R₁ independently of each other is fucosyl or H R₄ independently of each other is sialyl or H, with the proviso that at least one R₁ or R₄ is not H; compounds of general formula 3 and salts thereof

wherein R₁ is fucosyl or H, R₂ is selected from N-acetyl-lactosaminyl and lacto-N-biosyl groups, wherein the N-acetyl lactosaminyl group may carry a glycosyl residue comprising one or more N-acetyl-lactosaminyl and/or one or more lacto-N-biosyl groups; any N-acetyl-lactosaminyl and lacto-N-biosyl group can be substituted with one or more sialyl and/or fucosyl residue, R₃ is H or N-acetyl-lactosaminyl group optionally substituted with a glycosyl residue comprising one or more N-acetyl-lactosaminyl and/or one or more lacto-N-biosyl groups; any N-acetyl-lactosaminyl and lacto-N-biosyl group can be substituted with one or more sialyl and/or fucosyl residue; and/or compounds of general formula 4 and salts thereof

wherein R₁ independently of each other is fucosyl or H R₄ independently of each other is sialyl or H with the proviso that at least one R₁ or R₄ is not H.
 9. The method according to claim 8, wherein compounds of formulae 1 and 2 are further characterized by general formulae 1a, 1b or 2 or salts thereof

and compounds of formulae 3 and 4 are further characterized by general formulae 3a, 3b or 4 or salts thereof

wherein R, R₁ and R₄ are as defined in claim 8, R_(2a) is N-acetyl-lactosaminyl group optionally substituted with a glycosyl residue comprising one N-acetyl-lactosaminyl and/or one lacto-N-biosyl group; any N-acetyl-lactosaminyl and lacto-N-biosyl group can be substituted with one or more sialyl and/or fucosyl residue, R_(3a) is H or N-acetyl-lactosaminyl group optionally substituted with a lacto-N-biosyl group; any N-acetyl-lactosaminyl and lacto-N-biosyl group can be substituted with one or more sialyl and/or fucosyl residue, R_(2b) is lacto-N-biosyl group optionally substituted with sialyl and/or fucosyl residue, R_(3b) is H or N-acetyl-lactosaminyl group optionally substituted with one or two N-acetyl-lactosaminyl and/or one lacto-N-biosyl group; any N-acetyl-lactosaminyl and lacto-N-biosyl group can be substituted with one or more sialyl and/or fucosyl residue.
 10. The method according to claim 8, wherein the N-acetyl-lactosaminyl group in the glycosyl residue of R_(2a) in general formula 1a or 3a is attached to another N-acetyl-lactosaminyl group with 1-3 interglycosidic linkage, the lacto-N-biosyl group in the glycosyl residue of R_(2a) in general formula in or 3a is attached to the N-acetyl-lactosaminyl group with 1-3 interglycosidic linkage, the lacto-N-biosyl group in the glycosyl residue of R_(3a) in general formula 1a or 3a is attached to the N-acetyl-lactosaminyl group with 1-3 interglycosidic linkage, the N-acetyl-lactosaminyl group in the glycosyl residue of R_(3b) in general formula 1b or 3b is attached to another N-acetyl-lactosaminyl group with 1-3 or 1-6 interglycosidic linkage, the lacto-N-biosyl group in the glycosyl residue of R_(3b) in general formula 1b or 3b is attached to the N-acetyl-lactosaminyl group with 1-3 interglycosidic linkage.
 11. The method according to claim 8, wherein general formula 1a represents the R-glycosides of lacto-N-neotetraose, para-lacto-N-hexaose, para-lacto-N-neohexaose, lacto-N-neohexaose, para-lacto-N-octaose and lacto-N-neooctaose optionally substituted with one or more sialyl and/or fucosyl residue, general formula 1b represents the R-glycosides of lacto-N-tetraose, lacto-N-hexaose, lacto-N-octaose, iso-lacto-N-octaose, lacto-N-decaose and lacto-N-neodecaose optionally substituted with one or more sialyl and/or fucosyl residue, general formula 3a represents lacto-N-neotetraose, para-lacto-N-hexaose, para-lacto-N-neohexaose, lacto-N-neohexaose, para-lacto-N-octaose and lacto-N-neooctaose optionally substituted with one or more sialyl and/or fucosyl residue, and general formula 3b represents lacto-N-tetraose, lacto-N-hexaose, lacto-N-octaose, iso-lacto-N-octaose, lacto-N-decaose and lacto-N-neodecaose optionally substituted with one or more sialyl and/or fucosyl residue.
 12. The method according to claim 8, wherein the fucosyl residue attached to the N-acetyl-lactosaminyl and/or the lacto-N-biosyl group is linked to the galactose of the lacto-N-biosyl group with 1-2 interglycosidic linkage and/or the N-acetyl-glucosamine of the lacto-N-biosyl group with 1-4 interglycosidic linkage and/or the N-acetyl-glucosamine of the N-acetyl-lactosaminyl group with 1-3 interglycosidic linkage, the sialyl residue attached to the N-acetyl-lactosaminyl and/or the lacto-N-biosyl group is linked to the galactose of the lacto-N-biosyl group with 2-3 interglycosidic linkage and/or the N-acetyl-glucosamine of the lacto-N-biosyl group with 2-6 interglycosidic linkage and/or the galactose of the N-acetyl-lactosaminyl group with 2-6 interglycosidic linkage.
 13. The method according to claim 8, wherein the compounds are selected from the group consisting of: R-glycosides of 2′-fucosyllactose, 3-fucosyllactose, 2′,3-difucosyllactose, 3′-sialyllactose, 6′-sialyllactose, 3′-sialyl-3-fucosyllactose, lacto-N-tetraose, lacto-N-neotetraose, LNFP-I, LNFP-II, LNFP-III, LNFP-V, LST-a, LST-b, LST-c, FLST-a, FLST-b, FLST-c, LNDFH-I, LNDFH-II, LNDFH-III, DS-LNT, FDS-LNT I and FDS-LNT II, and salts thereof.
 14. The method according to claim 8, wherein said R-glycoside is a beta-anomer, and preferably wherein R is benzyl.
 15. The method according to claim 8, wherein the compounds are selected from the group consisting of: 2′-fucosyllactose, 3-fucosyllactose, 2′,3-difucosyllactose, 3′-sialyllactose, 6′-sialyllactose, 3′-sialyl-3-fucosyllactose, lacto-N-tetraose, lacto-N-neotetraose, LNFP-I, LNFP-II, LNFP-III, LNFP-V, LST-a, LST-b, LST-c, FLST-a, FLST-b, FLST-c, LNDFH-I, LNDFH-II, LNDFH-III, DS-LNT, FDS-LNT I and FDS-LNT II, and salts thereof.
 16. The method according to claim 1, wherein step a) comprises providing at least one compound or a mixture of the compounds characterized by general formula 5

R′ independently is fucosyl or H, with the proviso that at least one R′ is fucosyl R* is a group removable by hydrogenolysis or H, and optionally providing at least one compound or a mixture of the compounds, selected from the group consisting of: optionally sialylated lactose derivatives of general formula 6 and salts thereof:

wherein R* is a group removable by hydrogenolysis or H, R″ independently of each other is sialyl or H, lacto-N-tetraose (LNT):

lacto-N-tetraose (LNT) derivatives of the following formula:

wherein R is a group removable by hydrogenolysis; lacto-N-neotetraose (LNnT):

lacto-N-neotetraose (LNnT) derivatives of the following formula:

wherein R is a group removable by hydrogenolysis; and wherein in step b) at least one enzyme comprising a transfucosidase activity is added to the at least one compound or mixture of compounds provided according to step a).
 17. The method according to claim 16, wherein step a) comprises providing 2′-fucosyllactose or 3-fucosyllactose, and one further compound selected from the group consisting of 2′-fucosyllactose, 3-fucosyllactose, 3′-sialyllactose, 6′-siallyllactose, LNT and LNnT.
 18. The method according to claim 16, wherein incubation leads to a fucosylated human milk oligosaccharide or mixture of human milk oligosaccharides, particularly to 2′,3-difucosyllactose, 3-fucosyl-3-sialyllactose, fucosylated LNT or fucosylated LNnT, or mixture thereof.
 19. The method according to claim 1, wherein the compounds obtained in the incubation step are subjected to a hydrogenolysis reaction.
 20. The method according to claim 1, wherein the compounds obtained in the incubation or hydrogenolysis step are subsequently purified, preferably via crystallization or precipitation.
 21. The method according to claim 1, further comprising the step of spray-drying the compounds obtained in step c), d) or e).
 22. The method of claim 1, further comprising addition of the compounds obtained in the incubation or hydrogenolysis step to a consumable product, wherein the consumable product is preferably at least one of a pharmaceutical or nutritional formulation.
 23. The method of claim 1, further comprising the addition of pharmaceutically acceptable carriers and/or the addition of prebiotics to the compounds obtained in the incubation or hydrogenolysis step.
 24. (canceled)
 25. (canceled)
 26. The method according to claim 2, wherein in step d): only one HMO or derivative or precursor thereof is made as a result of step c), and further where both: only two compounds are provided in step a) of which one is 3′-sialyllactose or a sialylated lactose derivative of general formula 2 or 4, and the enzyme comprising a transglycosidase activity added in step b) is an enzyme comprising a trans-sialidase activity, at least steps a) and c) or steps b) and c) are repeated.
 27. The method according to claim 2, wherein step a) comprises providing at least one compound or a mixture of the compounds characterized by general formula 5

R′ independently is fucosyl or H, with the proviso that at least one R′ is fucosyl R* is a group removable by hydrogenolysis or H, and optionally providing at least one compound or a mixture of the compounds, selected from the group consisting of: optionally sialylated lactose derivatives of general formula 6 and salts thereof:

wherein R* is a group removable by hydrogenolysis or H, R″ independently of each other is sialyl or H, lacto-N-tetraose (LNT):

lacto-N-tetraose (LNT) derivatives of the following formula:

wherein R is a group removable by hydrogenolysis; lacto-N-neotetraose (LNnT):

lacto-N-neotetraose (LNnT) derivatives of the following formula:

wherein R is a group removable by hydrogenolysis; and wherein in step b) at least one enzyme comprising a transfucosidase activity is added to the at least one compound or mixture of compounds provided according to step a).
 28. The method according to claim 27, wherein step a) comprises providing 2′-fucosyllactose or 3-fucosyllactose, and one further compound selected from the group consisting of 2′-fucosyllactose, 3-fucosyllactose, 3′-sialyllactose, 6′-siallyllactose, LNT and LNnT. 